Category: Network-attached storage

The NAS as an on-premises edge-computing device for cloud services

QNAP TS-251 2-bay NAS

QNAP TS-251 2-bay NAS – units like this could become a capable edge-computing device

The high-end network-attached storage system is a device able to augment the cloud computing trend in various forms. This is by becoming a local “edge processor” for the cloud-computing ecosystem and handling the data that is created or used by end-users local to it.

High-end network-attached-storage systems

We are seeing the rise of network-attached-storage subsystems that are capable of running as computers in their own right. These are typically high-end consumer or small-business devices offered by the likes of QNAP, Synology or NETGEAR ReadyNAS that have a large app store or software-developer community.

The desktop variants would be the size ranging form half a loaf of bread to a full bread loaf, with some rack-mounted units about the size of one or two pizza boxes.This is compared to servers that were the size of a traditional tower computer.

But some of the apps work alongside public cloud-driven online services as a client or “on-ramp” between these services and your local network. A typical use case is to synchronise files held on an online storage service with the local storage on the NAS unit.

These high-end network-attached-storage devices are effectively desktop computers in their own right, with some of them using silicon that wouldn’t look out of place with a traditional desktop computer. Some of these machines even support a “local console” with a display connection and USB connections that support keyboards and mice.

Cloud computing

Cloud computing takes an online-service approach to computing needs and, in a lot of cases, uses multiple computers in multiple data centres to perform the same computing task. This is typically to host the data in or close to the end-user’s country or to provide a level of scalability and fault-tolerance in the online service approach.

Lot 3 Ripponlea café

A cafe like this could benefit from big-business technology without paying a king’s ransom thanks to cloud computing

Small businesses are showing an interest in cloud-driven computing solutions as a way to come on board with the same things as the “big end of town” without paying a king’s ransom for hardware necessary for an on-premises computing solution. In some cases, it is also about using different endpoint types like mobile-platform tablets for daily use or as a management tool, underscoring such concepts as low cost or portability that some endpoints may offer.

Typically, this kind of computing is offered “as a service” where you subscribe to the service on a regular, usually monthly or annual, basis rather than you spending big on capital expenses to get it going.

But, due to its nature as an always-online service, cloud computing can cause reliability and service-availability issues if the Internet connection isn’t reliable or the service ends up being oversubscribed. This can range from real-time services suffering latency towards a cloud-computing experience becoming unresponsive or unavailable.

Then there is the issue of privacy, data security, service continuity and data sovereignty which can crop up if you change to a different service or the service you use collapses or changes hands. It can easily happen while cloud-computing faces points of reckoning and the industry goes in to consolidation.

Edge computing

But trends that are being investigated in relationship to the “Internet Of Things” and “Big Data” are the concepts  of “edge” and “fog” computing. It is based around the idea of computing devices local to the source or sink of the data that work with the locally-generated or locally-used data as part of submitting it to or fetching it from the cloud network.

It may allow a level of fault-tolerance for applications that demand high availability or permit scalability at the local level for the cloud-computing application. Some systems may even allow for packaging locally-used data in a locally-relevant form such as for online games to support local tournaments or an online movie service to provide a local storage of what is popular in the neighbourhood.

The ideas associated with “edge” and “fog” computing allow for the use of lightweight computer systems to do the localised or distributed processing, effectively aggregating these systems in to what is effectively a heavyweight computer system. It has been brought about with various early distributed-computing projects like SETI and Folding@Home to use personal computers to solve scientific problems.

What is serving the edge-computing needs

Qarnot Q.Rad press image courtesy of Qarnot

This Qarnot Q.Rad heater is actually a computer that is part of edge computing

Some applications like drones are using the on-device processing to do the local workload. Or we are seeing the likes of Qarnot developing edge-computing servers that heat your room or hot water with the waste heat these computing devices produce.  But Amazon and QNAP are working on an approach to use a small-office NAS as an edge-computing device especially for Internet-Of-Things applications.

The NAS serving this role

Here, it is about making use of these ubiquitous and commonly-available NAS units for this purpose as well as storing and serving data that a network needs. In some cases, it can be about the local processing and storing of this locally-generated / locally-used data then integrating the data with what is available on the cloud “backbone”.

For some applications, it could be about keeping enough data for local needs on the NAS to assure high availability. Or it could be about providing scalability by allowing the NAS to do some of the cloud workload associated with the locally-generated data before submitting it to the cloud.

Netgear ReadyNAS

The NETGEAR ReadyNAS on the right is an example of a NAS that is capable of being an edge-computing node

This may be of importance with IT systems that are moving from a totally on-premises approach towards the use of cloud-computing infrastructure with data being stored or processed online. It is where the focus of the cloud infrastructure is to make business-wide data available across a multi-site business or to provide “portable access” to business data. Here, a NAS could simply be equipped with the necessary software to be a smart “on-ramp” for this data.

For small and medium businesses who are moving towards multiple locations such as when a successful business buys another business in another area to increase their footprint, this technology may have some appeal. Here, it could be about doing some pre-processing for data local to the premises before submitting to the cloud as part of an online management-information-system for that small effort.  As well, it could be about keeping the business-wide data “in-sync” across the multiple locations, something that may be important with price lists or business-wide ledgers.

This kind of approach works well with the high-end NAS units if these units’ operating platforms allow third-party software developers to write software for these devices. It can then open up the possibilities for hybrid and “edge” computing applications that involve these devices and the network connectivity and on-device storage that they have.

Conclusion

What needs to happen is that the high-end network-attached-storage systems of the Synology or QNAP kind need to be considered as a hardware base for localised “edge computing” in an online “cloud-computing” setup.

This can be facilitated by the vendors inciting software development in this kind of context and encouraging people involved in online and cloud computing to support this goal especially for small-business computing.

Setting up a mobile NAS to work with your home network

WD MyPassport Wireless mobile NAS

The WD MyPassport Wireless mobile network-attached storage – can offer data to the host Wi-Fi network when set up in hotspot mode

Increasingly, data-storage device manufacturers are adding to their mobile network-attached storage devices the same kind of network-based data storage and access features typically offered with a standard desktop NAS device. This is rather than these devices just being a lightweight file server for smartphones and tablets connected to the device’s own Wi-Fi access point.

I had previously reviewed one of these devices in the form of the WD MyPassport Wireless mobile NAS which demonstrated this kind of functionality. In the review, I had called out the DLNA-compliant media server that was part of that mobile NAS’s feature set, where you had the ability to show your photos and videos on one of the latest Smart TVs via the home network the TV is connected to.

Mobile NAS with hotspot mode set for “secure” or “private” mode

As well, some of the increasingly-sophisticated devices like the WD MyPassport Wireless Pro also are offering the same kind of Samba-based (SMB / CIFS) file transfer method that you can do with other NAS devices so you can transfer resources to these devices using your regular computer’s operating-system’s file manager and its network file transfer protocols. Similarly, the devices may implement FTP, WebDAV or other common network-file-transfer protocols primarily to allow you to upload photos and footage from your Wi-Fi-capable digital camera or camcorder to the mobile NAS if the camera honours these standard protocols.

How to have this work properly?

Here your mobile NAS unit needs to be set up for connection to an existing small Wi-Fi network as a client device of that network. It also needs to be set up to share its resources to that client network in addition to the network it creates using its own wireless access point.  Most of this configuration that I would be talking about here would be something you would do using the vendor-provided native mobile-platform app or, perhaps, a Web page that the mobile NAS creates as its management page.

Mobile NAS with hotspot functionality set up for file sharing mode

Typically, you may set this up as part of enabling a “Share Wi-Fi Connection”, “Wi-Fi Hotspot” or similar function that effectively shares a logical network connection between multiple devices that connect to the portable NAS’s access point. This function is similar to what most travel routers offer as a way to share the one logical (and usually permitted) connection to a hotel’s guest-access Wi-Fi service amongst the personal computing devices you and your travelling companions own. Similarly, this same function creates a “trust circle” between multiple devices connected to the mobile NAS’s access point allowing them to be discovered by each other even if the public-access Wi-Fi network that the NAS is connected to is configured properly with client isolation enabled.

When you enable the “hotspot” function on a sophisticated mobile NAS like the WD MyPassport Wireless / Wireless Plus series or the Seagate Wireless Plus, you will have an option to set this function to work in a “private” or “secure” mode or a “sharing” mode.  In the “private” mode, the data held on the NAS becomes available only to devices on the Wi-Fi network created by the mobile NAS’s access point. Conversely, the “sharing” mode will make the data available to devices on the network which has the Wi-Fi segment you connected the mobile NAS to as part of the “hotspot” mode.

Availability of data held on mobile NAS Sharing mode Secure / Private mode
Host wireless network Yes No
Wireless network created by mobile NAS’s access point Yes Yes

To allow the mobile NAS to share its resources on your home network, you need to enable the “sharing” mode or disable the “secure” or “private” mode while setting up the “hotspot” functionality. It is a wise practice not to use the “sharing” mode on a Wi-Fi network used as a public-access network and this function wouldn’t work with these networks that are properly set up with client isolation enabled.

What can the manufacturers do to improve the Wi-Fi bridging functionality on these devices?

The “Wi-Fi hotspot” or “Shared Wi-Fi” functionality could be improved upon by allowing users to create preset operating modes for particular Wi-Fi networks. This would work in a similar way to the way Windows allows the user to classify each network they connect to as being a “home”, “work” or “public” network, causing it to adopt an exposed persona suitable for your home or office network or a private person for that public-access Wi-Fi network. Such parameters could be to determine whether to share resources with the host network or to always clone the client device’s MAC address when connecting along with remembered Wi-Fi network passwords.

Here, as a user connects the mobile NAS to a Wi-Fi network for “Shared Wi-Fi” operation, they are invited to save the configurations they have established for that network. Then, when they reconnect to that network, the mobile NAS assumes the operating modes that the user previously defined. These details can be referenced by the host network’s ESSID or a user-defined name for that network.

Conclusion

Once you know how to set up that highly-capable mobile NAS device and exploit the “private” or “shared” operating modes that these devices offer with setting up the “Shared Wi-Fi” or “hotspot” mode, you can then use them to make resources held therein available to other small networks you connect them to.

DLNA 4 and Vidipath facilitate elaborate TV user interfaces for network devices

Thecus N5810PRO Small Business NAS press photo courtesy of Thecus

NAS units will be required to provide a rich user interface on the big screen without the need of an app

I have had a look through the DLNA 4.0 and VIDIPATH standards and found a feature that these standards do provide for in the form of a “remote user interface”. This is where another server device can provide a graphically-rich user interface on a separate client device typically in the form of a Smart TV or video peripheral. It works very much in a similar frame to how Web browsing, where you have Web pages hosted on Web servers and streamed over a network to a Web browser existing on a client device.

The standards that are supported in this context are HTML5 and RVU (pronounced R-View) which facilitate this graphically-rich user interface. It was pitched more at pay-TV operators who provide their customers a PVR or media gateway and want to share the same user interface across all of the smart TVs, connected video peripherals (Blu-Ray players, games consoles, network media players), regular desktop/laptop computers and mobile computing devices (smartphones, phablets and tablets).

Here, this would facilitate operator-provided video-on-demand, interactive TV services, the electronic programme guide and value-added services but allow the operator to present these services with their “skin” (branding and user experience) on all of the screens in a customer’s household. This is in contrast to services like programme guides, PVR content collections and recording schedules being presented using the device manufacturer’s user interface which may not be consistent especially at the lower end of the market. It wouldn’t matter whether the server device was “headless” (without a display or control surface) like a broadcast-LAN tuner or had a display and control surface like the typical set-top PVR with its own remote control and connected to the TV in the main lounge area.

But this technology appeals to another class of devices beyond the pay-TV set-top boxes and media gateways.

Increasing network-attached-storage vendors are partnering with software developers to develop and deploy advanced media-server software in their consumer-focused NAS products. Examples of these include the Plex Media Server being packaged with newer Western Digital premium consumer NAS products and the media server software that Synology are packaging as part of their latest DSM 6 NAS software. Typically these offer functionality like rich media information or improved search / browse functionality.

Some of the NAS devices offer PVR software that works with USB digital-TV-tuner modules or broadcast-LAN tuner boxes and are targeted towards markets where free-to-air TV or pay-TV delivered without operator-supplied equipment is highly valued.

As well, a lot of consumer-focused NAS devices are being marketed in the concept of the “personal cloud” and these devices could benefit from a rich user interface that takes advantage of smart TVs.

It also includes the possibility of Secure Content Storage Association pushing their Vidity “download-to-own” platform as a way to deliver the same kind of collectability and rich user experience that the DVD and Blu-Ray box-sets are known for when supplying sell-through video content “over the wire” or allowing customers to download DVD and Blu-Ray content to their home networks. This could also encompass using a NAS as an “offload device” for extra binge-watch content that you bring in using a PVR.

More and more, manufacturers will look at ways to add value to NAS devices or broadcast-LAN tuner devices as a way to have customers buy the newer devices rather than hang on to older devices.

When NAS suppliers want to offer this kind of functionality, they either implement a Web user interface which may work best for regular computers and tablets with you needing to know IP addresses or device network names, or you are having to download and install companion client apps into your client devices. This doesn’t really work well with any 10-foot “lean-back” experience.

But the reality is that this software can exploit RVU or HTML5 remote-user-interface standard technology to realise the user-interface images on to the regular television screen. Typically, all it requires is that the devices exploit their Web server software to implement the RVU or HTML5 remote-user-interface technology and use UPnP which is already used for the DLNA content server functionality to expose this content to TVs and similar devices.

For that matter, the ability to print out content from an interactive-TV show should be integrated in to RVU or HTML5 technology because some shows and advertising like cookery shows encourage the printing out of value-added content for users to benefit from this content.

To the same extent, the hotel applications could take this further by opening up virtual content sources for things like in-house video-on-demand or gaming; or even provide a user interface to services like in-room dining or booking use of day-spa facilities.

What needs to happen is that the remote user interface technology can be exploited beyond the set-top-box or media-gateway application and taken further to NAS or other server-role devices on a home or business network for a proper 10-foot experience.

Your Chromebook can now work with your SMB-capable NAS

Article

WD MyCloud EX2 dual-disk NAS

These NAS units can now work with your Chromebook thanks to a Google SMB/CIFS file-system hook

Chromebooks can now seamlessly access Windows network file shares | PC World

Download link (Chrome OS)

My Comments

An issue you may find with the newer Chrome OS is that you could become stranded when it comes to gaining access to files. This may place limitations on your Chromebook’s utility value and you may find it serving as a glorified tablet.

Now you can download a Google-created app which serves primarily as a “hook” between Chrome OS and the SMB/CIFS network file exchange protocol implemented in just about all of the desktop operating systems for file sharing and in every network-attached storage device on the market.

This app takes advantage of an API made available for the Chrome OS platform that allows people to create software that links this platform with various file-storage systems and has been published as an open-source program, due to it being based on the Samba SMB/CIFS software used in every NAS. This could open up paths for creating various “hooks” for operating systems and computing platforms that make them work with these NAS units.

The article raised the issue of Dropbox and Microsoft writing native “hooks” for their cloud storage systems rather than users of these systems using flaky software to have their Chromebook work with Dropbox or OneDrive.

QNAP releases an ultra-compact SSD NAS

Article – From the horse’s mouth

QNAP QNAP logo courtesy of QNAP

TBS-453A NASBook Ultra-Compact SSD NAS

Product Page

My Comments

QNAP has just lately offered the TBS-453A NASBook which is an ultra-compact 4-drive NAS that is designed to work with solid-state drives rather than hard disks,

But this solid-state-drive NAS is a different breed to the portable NAS units offered to mobile users who exchange data between laptops and tablets. This is about Ethernet rather than Wi-Fi connectivity along with a 4-disk RAID array for performance or data safety, and increased functionality thanks to a desktop-grade NAS app store offered by QNAP.

The drives that are preferred for this device are the M.2 type that are typically used for Ultrabooks and 2-in-1s with this device being about the size of a B5 notebook. As well, it is powered by a 19-volt power brick but can accept voltages between 10 volts and 20 volts DC. This makes it suitable for a wide range if industrial and similar uses and could appeal to automotive and marine use, if there was a way to support externally-switched power control expected for such use.

It also has a 4-port Ethernet switch for one network along with a single Gigabit Ethernet socket for another network and this can be set up to work effectively like a router or to serve its own network.

As well, like other QNAP NAS units, this implements the QTS operating system with an increasing array of apps for business and personal use. But it also can be set up as a Linux computer by implementing a virtualised dual-operating-system setup and has the necessary “console” connections for this purpose. That is HDMI for display and audio connection along with USB connections for keyboard and mouse purposes. Like some recent QNAP NAS units, it also has its own audio interface which makes it appeal as a multimedia computer in its own right.

You can also expand this book-size NAS to work with a regular disk array by installing UX-800P and UX-500P multi-disk expansion modules this allowing you to create RAID disk arrays with these disks.

Tool or toy?

This kind of “far-fetched” cutting-edge network-attached-storage device could be easily dismissed as a toy rather than a tool, but there are some applications where it could earn its keep as a tool.

One would be to exist as a highly-capable Ethernet-connected portable NAS or server device that you use in a “mobile-office” setting. Similarly, you could see this being used with a home network where you want the multimedia functionality like DLNA Network Media Server functionality looked after but without dealing with a noisy or power-inefficient device. This would also win favours with home-AV manufacturers and distributors who are showcasing their network-capable hi-fi and home-theatre equipment at the hotel-based hi-fi shows like what the Chester Group are running. As well, QNAP are pitching this device in the Internet Of Things and building-security applications scenarios where this NAS could record data from sensor-type devices or visual images from network cameras yet be able to work with low power demands.

QNAP could see the TBS-453A as an effort to approach vehicle and marine applications for NAS devices along with courting mobile workgroups, remote data collection or other setups where portability, low power consumption or reduced operating noise are highly valued.

Xiaomi raises the bar for routers with internal storage

Articles – From the horse’s mouth

Seagate

A Wireless Router with 6TB Storage? | Digital Den comsumer blog

Xiaomi

Mi WiFi Router 2 With 6Tb

Product Page

My Comments

Seagate has helped another manufacturer raise the bar for a consumer-grade router that has integrated storage.

Xiaomi had released to the Chinese market the Mi WiFi Router 2 with 6Tb storage on board. This is provided with a Seagate hard disk that is optimised for video-surveillance applications, with this hard disk able to handle continuous write operations and have a 1-million-hour mean-time-between-failure rate which leads to very high reliability. This is compared to most integrated-storage routers of this kind coming in with 1Tb hard disks typically optimised for regular computers.

The benefit that Seagate drew out was for storage integrated in an Internet-edge router is that the storage can serve as a waypoint for incoming and outgoing data especially if customers are using Internet services with not-so-good bandwidth. This is in addition to being an integrated network-attached storage for documents and media to be pulled up over the home network.

It could show that it is feasible to set up an integrated-storage router with today’s NAS-grade or surveillance-grade hard disks having capacities in the order of at least 4Tb. As well, using application-level gateways and other software can make these devices work as staging posts for such applications as cloud storage services, software updates, content delivery and the like.

As well, the higher-capacity higher-reliability hard disks are showing up as a trend that will affect how network storage is designed.

SanDisk releases a wireless NAS as a memory key

Article

SanDisk's memory key that is a wireless mobile NAS

SanDisk’s memory key that is a wireless mobile NAS

SanDisk Announces Bigger, Cheaper Wi-Fi Flash Drive | SmallNetBuilder

From the horse’s mouth

SanDisk

SanDisk Connect Wireless Stick

Press Release

Product Page

My Comments

There are a number of “wireless network-attached storage” devices on the market that are primarily pitched at people who use mobile devices and want to have network storage for these devices.

These devices typically work as their own Wi-Fi networks and work alongside a Web front that they provide or a native app provided by the vendor for the main mobile platforms to allow you to use them as networked storage for these devices. But those of you who use regular computers are typically required to connect these wireless NAS devices to the computer’s USB ports and use them as if they are removable storage devices.

SanDisk has released the the latest of these devices as the wireless networked equivalent of the USB memory key a.k.a. thumbdrive or jumpdrive. This device, known as the Connect Wireless Stick is the same size as a large USB memory key but has its own Wi-FI access point and Web server. There is an integrated battery and you can plug it in to a computer or USB charger to charge this device. In this same context, it can be used as a USB flash drive for the connected computer or multimedia device.

It also has the ability to work as a Wi-FI bridge for Internet connection through you setting up the Internet Connection in the SanDisk mobile app. But being a low-powered device, the SanDisk Connect Wireless Stick would have the ability to stream video content to three client devices concurrently rather than five for most of the hard-disk-based devices. Oh yeah, hang this around your neck to view content you have loaded on to it or share stuff with your buddies sitting at your lunch table in the caf – no need to forget it when you head to class.

But there are a lot of issues to be raised with these devices and how they interlink with the rest of the world. One of these involves the issue of manufacturers writing their own apps for their devices and requiring  users to install and use these apps to see full benefit from them. Here, the wireless NAS devices could use a common WebDAV or CIFS client and UPnP / Bonjour functionality for simplified discovery including the ability to discover the device’s Web page in that context. As well, the device could be managed through a password-protected Web page. This would allow for, at the most, one app to be deployed on your mobile device.

They would also have to support WebDAV and CIFS along with HTTP for two-way file transfer to and from hosts along with appropriate DLNA abilities for interaction with consumer-electronics devices. Similarly the wireless NAS devices would have to support working as clients or access points for small private networks i.e. home / small-business networks and as “go-between” bridges for public networks. This kind of functionality would require WPS and manual-entry setup for small private networks along with Wi-Fi Passpoint setup for public networks.

In essence, the wireless network-attached-storage device should be a point of innovation for everything that works with it. This includes public and private networks, consumer-electronics and photography devices along with system software for regular and mobile computing devices.

QNAP announces a 10GbE-capable 5-bay NAS

Article QNAP logo courtesy of QNAP

QNAP Announces 10GbE Ready AMD NAS | SmallNetBuilder

From the horse’s mouth

QNAP

TS-563 Turbo NAS – Product Page

My Comments

QNAP have raised the bar when it comes to defining the a business-ready premium network-attached-storage unit. This is in the form of the TS-563 Turbo NAS which is a 5-bay desktop unit capable of a RAID 5 with “hot-spare” disk and hot-swapping.

But the NAS uses an AMD quad-core processor fit for a regular computer as its brain and can support RAM of up to 16Gb. As well, the unit has a PCIe expansion slot so it can be connected to a 10GbE Ethernet network connection once you purchase and install a PCIe 10GbE interface card. It is highlighting the fact that the premium small-business NAS units are approaching the same kind of power that was expected out of a dedicated tower-style computer that was used as a small business’s server but are the same size as a traditional kitchen breadbox.

This NAS has 5 USB ports with one being on the front for “walk-up” connectivity. This isn’t just to connect a backup disk, a printer or a UPS to permit orderly and safe shutdown during a blackout. Rather, it is also to allow you to connect up to two of QNAP’s UX-series expansion enclosures for increased disk capacity. These enclosure could allow you to create larger multi-disk storage setups with varying levels of capacity and fault-tolerance.

Even though this is a NAS unit pitched at the business market, the QNAP TS-563 Turbo NAS still runs the QTS 4.1 operating system which has all the expectations and software to have it become either a branch-office file server, small-business NAS or home media server.

This is a sign of things to come for small-business computing where you can have a small NAS working as a data hub for these businesses yet you still have the performance and power of a traditional “tower-style” PC-based server.

What are the multiple drive layouts available in your NAS

WD MyCloud EX2 dual-disk NAS

WD MyCloud EX2 2-disk NAS – has a 2-disk RAID setup

All network-attached-storage units that have two or more drive bays in them offer different ways to make use of the hard disks installed in these drive bays. These are primarily about creating one logical disk volume out of the many disk drives.

You may also find multiple-disk arrays being implemented in so-called “Direct Attached Storage” devices which connect to your computer as if they are a peripheral or are integrated in the computer. These are typically used for computer setups where read-write performance for secondary storage is considered important like video editing or for computers that work as servers.

WD MyCloud EX4, WD MyCloud EX2, WD Red 6Tb hard disk

WD MyCloud EX4 NAS – can be set up as a 4-disk RAID array

The most common setups are described as “RAID” or “Redundant Array Of Independent Disks”. These setups gang multiple hard disks (or solid-state drives) to improve data throughput, effective disk capacity or system fault-tolerance.

Multi-Drive Disk setups

RAID setups

It is important to remember that a RAID setup that is about fault tolerance doesn’t obviate the need to back up the contents of a NAS. This is something you can do with a USB hard disk connected to the NAS, another NAS on the same network or connected via the Internet or an online storage or backup service.

RAID 0

RAID 0 Data striping data layout

RAID 0 Data Striping across disks

Here, this creates one logical volume with the data spread across the disks, a method known as “striping”. Each block of data is sequentially stored across each physical disk rather than a disk being filled with data then another disk being subsequently filled with data.

This allows for increased capacity and read / write data throughput, but loses on fault tolerance because the disk array is no good and the data is lost if one of the drives fails.

Volume Capacity: Number of Disks x Size of smallest disk

RAID 1

RAID 1 disk mirroring data layout

RAID 1 – Disk Mirroring

This setup creates a logical volume with the data duplicated on each physical drive. a method known as “mirroring”.

The main advantage here is increased fault-tolerance because if a disk dies, you still have access to the the data on the other disk. There is also another advantage of increased read throughput because both physical disks can be read at the same time.

The only limitations here are the volume capacity which is the size of the smallest disk in the array along with the write speed because the disk controller has to write the same data to multiple disks. It is infact a preferred RAID array setup for a 2-bay NAS due to the fault-tolerance.

Volume Capacity= Size of smallest disk in the bunch

RAID 5

RAID 5 Data Striping with parity Data layout

RAID 5 Data Striping with a parity block

This setup works between data capacity and fault tolerance in a very interesting way. It is because the RAID 5 setup creates “parity” data. This is used in computing as a fault-tolerance measure because an algorithm can use this data along with the “known-to-be-good” data to reconstitute data lost in transmission.

Here, a RAID 5 array stripes data across the physical disk collection but inserts a block of parity data at regular intervals as part of this “striping” so as to create some form of fault-tolerance. Then the RAID 5 disk controller reconstitutes data from parity and available “known-to-be-good” data if things start to go wrong with a disk.

The advantages in these setups are the disk capacity, the read throughput and the fault tolerance but there is a performance reduction for those systems that do a lot of data writing.

Volume Capacity: (Number of disks – 1) x smallest disk size

RAID 6

RAID 6 Data striping and two-block parity data layout

RAID 6 Data striping with two-block parity

RAID 6 works in a similar manner to RAID 5 in that it stripes data across multiple physical disks and creates a parity block for fault-tolerance. But a RAID 6 array creates another parity block to increase the amount of fault tolerance in the setup.

Volume capacity: (Number of disks-2) x smallest disk size

RAID 10 (1+0)

RAID 10 data layout

RAID 10 A combination of data striping and disk mirroring

A setup that is used with 4-disk RAID arrays is the RAID 10 array also known as the RAID 1+0 array which is a combination of both the RAID 1 setup and the RAID 0 setup.

Here, there are two collections of disks with one collection keeping copies of the data held on the other collection. Each collection has its data “striped” across the disks for capacity and performance.

The core benefit with a RAID 10 setup is that there is increased write throughput which can come in handy with write-intensive setups like databases. This is in addition to the fault tolerance provided by mirroring along with the read performance provided by striping.

Volume Capacity: Combined size of two of the smallest disks

Non-RAID setups

JBOD data layout

JBOD – Disks as separate volumes

JBOD

This setup, known as “Just a Bunch Of Disks” is simply about each physical disk being treated by the NAS as a separate logical volume. It can be useful if you want to maintain separate data on each disk under a separate volume name.

Spanning

Disk Spanning data layout

Disk Spanning, sometimes known as JBOD by some manufacturers

The “spanning” setup simply is based on data filling up one disk then filling up another disk in that same volume.

Array Type Disks Capacity Performance Fault
Tolerance
RAID 0 Min: 2 Yes Yes
RAID 1 Min: 2 Yes
improved read
Yes
Copied disks
RAID 5 Min: 3 Yes Yes
improved read
Yes
Parity
RAID 6 Min: 4 Yes Yes
improved read
Yes
dual parity
RAID 10 Min: 4
Even number of disks
Yes
improved write
Yes
Copied disk arrays
JBOD Logical volume / disk Yes
Spanning Min: 2 Yes

Different options available

Automatic RAID setups

Netgear ReadyNAS

The NETGEAR ReadyNAS on the right can implement X-RAID automatic RAID setup

An increasing number of manufacturers use an “automatic RAID” setup like Synology’s Hybrid RAID or NETGEAR’s X-RAID. These are RAID setups that are optimised to mix different-sized hard disks so that these arrays work to maximise useable capacity, disk performance and fault-tolerance.

Manufacturers pitch these RAID setups for people new to NAS or disk-array management who are thinking about how much redundant storage is needed to balance capacity and fault tolerance. They also encourage the customers to “build out” a RAID array as and when they can afford the extra disks.

Hot-spare disks

Thecus N5810PRO Small Business NAS press photo courtesy of Thecus

Thecus N5810PRO small business NAS is able to implement a hot-spare disk for high RAID availability

Another feature offered mainly with small-business NAS units is the addition of a hot-spare disk. Such RAID arrays will have a separate hard disk that isn’t used unless one of the disks in that array fails.  These setups are preferred for environments where there is emphasis on a multi-disk array that is to be highly available at peak performance.

Hot-swap setups

An increasing number of prosumer and small-business NAS units come with a “hot-swap” functionality where you can swap out the hard disk while the NAS is in operation. This is more so for replacing faulty disks that are degrading a RAID array’s performance and is more relevant with RAID 1, RAID 5, RAID 10 and “automatic RAID” setups.

Upsizing a NAS’s RAID array

QNAP 2-disk NAS

QNAP 2-disk NAS – capable of setting up a highly-available high-performance RAID1 array

Upsizing a RAID array is something you could be tempted to do, especially as hard-disk prices gradually become cheaper and the time when one hard disk in a RAID array fails may be the time to upsize it.

But this can be difficult. Here, you would need to copy out all of the data to storage with the same volume capacity as your NAS’s current RAID array. Then you would have to simultaneously replace the disks in that array with units of the same but higher capacity before copying back the data. This may be easy to achieve with a 2-bay NAS.

Or you could migrate a 2-disk RAID 1 array in a 4-bay NAS to a RAID 5 array while adding a higher-capacity disk to that array. Here, you get increased capacity on the new disk due to the smaller disks being combined for real data use while space on the larger disk is allocated for parity data. Then you would need to swap out the small disks in that array with the larger disks as a way to gradually increase the volume’s useful size.

The automatic RAID setups make it easier to upsize your NAS as you can afford it and manage the right amount of redundant storage needed for your data.

The best RAID array setup for your needs and your NAS

The RAID array that you set your NAS up with depends on the number of drive bays the device has along with the number of disks you have. But these suggests are based on setups that are cost-effective yet yield high availability . They would also yield high read performance especially for multimedia applications. It is also a good idea to populate your multiple-bay NAS with drives of the same capacity when you are setting a new unit up.

A 2-bay NAS would be best set up as a RAID-1 array in order to implement the mirroring ability for high availability and increased read throughput which is necessary for video files streamed using DLNA.

A 4-bay NAS would be best set up as a RAID-5 array of at least three disks of the same size. There is the ability to make use of the capacity yet use the parity blocks to keep the data available should one of the disks keel over.

Conclusion

Once you understand how the various RAID and other multi-disk arrays work, you can choose the most cost-effective way to have your data stored for capacity, performance and high availability with your NAS.

SiliconDust has the idea of the NAS-based PVR for real

Article

WD MyCloud EX2 dual-disk NAS

WD MyCloud EX2 NAS – could be used as part of a network-based DVR

HDHomeRun Kickstarter wants to build the perfect DVR for you | Engadget

From the horse’s mouth

HDHomeRun

HDHomeRun DVR Kickstarter campaign

My Comments

Previously, I touched on the idea of the network-attached-storage becoming a DVR (digital video recorder) or PVR (personal video recorder) device courtesy of various apps being offered to some of these platforms. This is in contrast to set-top PVR devices of the TiVo or Foxtel IQ ilk which are based around their own tuners and hard-disk space.

Now SIliconDust, who make the HDHomeRun broadcast-LAN devices are developing a NAS-based DVR platform based around these devices. They got this idea up off the ground thanks to a highly-publicised Kickstarter crowdfund effort to get the idea up and off the ground.

What the goal is for the HDHomeRun effort is to create a flexible network-centric DVR setup which supports a regular computer or a NAS as the recording device. One of the key advantages is that you can add extra HDHomeRun broadcast-LAN boxes to record an increasing number of shows concurrently. This will earn its keep during the ratings season where the networks run all the good shows at once.

The system will be dependent on a computer, smartphone, tablet, TV or set-top box having a control app to book shows for recording and to play shows that you have recorded, along with a recording app integrated in the server computer or NAS that is doing all of the recording. All the client devices see multiple NAS units with this software as one source rather than as separate sources. It even has the ability to reserve one tuner to handle the common situation where one channel is running good shows one after another during the evening, while properly accommodating padding-out of recordings to deal with channels who overrun their shows to insert more commercials.

Personally, I would like to see this support the functionality associated with VIDIPATH such as having RVU user interfaces along with DLNA playback support, which could also earn its keep with smart TVs. But I see this as a way to bring forward the idea of the ultra-flexible DVR system for the home network.