A New Kind of Home Computer: Windows Home Server Preview
by Ryan Smith on September 4, 2007 1:00 PM EST- Posted in
- Systems
WHS As A Backup Suite
Although Microsoft is offering many features with WHS, it's WHS as a backup suite that is the single biggest feature of the OS. For Microsoft, this is more or less breaking new ground on an industry that is underdeveloped. At the corporate level there are numerous competting backup suites, but at the consumer level that WHS is targeting there's a handful of packages and Windows' own built-in backup system.
What does exist in the consumer space right now either does backups to the local disk, or if it's designed to do remote backups it does so via making whole copies of a disk, neither of which come close to what corporate software can do. WHS's backup abilities as a result are Microsoft's attempts to bring corporate features down to a home user, in line with the entire theme of WHS being a home's first server.
Central to the backup feature of WHS is the WHS Connector package, which serves as both the backup client for the machine and the key piece of software that integrates a machine into a WHS server. Once a new client is connected, the console can be used to configure the backup settings for that individual machine; out of the box all clients are set to backup between 12am and 6am, and most users will only need to enable backups for the new client. The client also has some control over the backup process without using the administrative console, and can initiate a backup at any time. Finally, the connector software allows WHS to keep track of the general health of each client and report on problems such as missing updates.
On the server side, anyone familiar with corporate backup software will undoubtedly find themselves at home with WHS. Along with scheduling backup times and triggering backups, administrators can exclude folders (but not files or file types) on a per-machine basis, view a list of backups, and manually purge old backups. To that extent WHS will also purge old backups automatically based on retention settings. All of this past the first backup is done incrementally to minimize space used and data transferred.
Furthermore, as the developer of Windows, Microsoft gets a strong ace up their sleeve in backup management: the volume shadow copy ability. We've previously talked about this in our Vista review as Microsoft is using it to run Vista's Previous Version feature, and on a server this ability is much more potent. Because WHS can back up the entire contents of a system (including the OS) it will back up a lot of redundant files; with a 10 client limit that's potentially 10 copies of Windows that need to be stored. Volume shadow copy can recognize the redundant clusters making up all those files and only store a single copy, so in a completely homogenous environment WHS will only need to store a single copy of Windows for the entire house.
The benefits of this further extend to user data, as any other duplicate files (e.g. music) will also only be stored a single time. The incremental backups that WHS does further benefit from the cluster level identification as WHS will only need to store the cluster changes of a file whenever a file is changed. Finally all of this is compressed to squeeze out whatever last bit of space savings can be found. All of these abilities due to volume shadow copy results in WHS backups being exceptionally efficient and making it possible to back up several machines with a drive much smaller than their combined drive space.
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ATWindsor - Sunday, September 9, 2007 - link
All NAS-boxes have horrible performance. (at least all I have seen). It hardly seems fair to use benchmarks from them, when this is a "Proper" computer, there are plenty of benchmarks from software raid 5 run on "real" computers to find, see this for instance:http://www.tomshardware.com/2004/11/19/using_windo...">http://www.tomshardware.com/2004/11/19/...appen/pa...
MDADM is as far as i know even faster, hower for whs it would likely be built on the software-raid of win2003.
Gholam - Sunday, September 9, 2007 - link
All NAS-boxes have horrible performance.Wrong. Proper NAS boxes have superb performance. Look at NetApp FAS270 for example. Of course a FAS270 in a typical configuration will run you in the $20,000-30,000 range.
That Tom's Hardware test is running a 2.8GHz CPU. http://www.pcpro.co.uk/reviews/121499/tranquil-t7h...">This WHS box is running a 1.3GHz VIA C7, for example.
Also, WHS is designed to be easily and transparently expandable by end-user using external drives. Please show me a RAID setup of any kind that will work in a mixed ATA/SATA/USB/FireWire configuration with drives of varying sizes.
ATWindsor - Sunday, September 9, 2007 - link
Ok, all consumer NAS-boxes then, I thought that much was implicit. It doesn't matter anyway, the point is that your comparison to a box like that isn't very good when it comes to "proving" that software-raid automatically has bad performance.A lot of boxes with WHS will be using a CPU that is better than a 1.3 Via, if the hardware isn't suited for the job, then you just don't run a software raid5, it's that easy.
I don't see how the WHS storage-pool is incompatible with raid as a concept, a raid-array presents itself as a single drive, more or less, wich can be merged into the storagepool if one feels like it.
Gholam - Monday, September 10, 2007 - link
Infrant ReadyNAS NV+ is a consumer level NAS. However, it's built on an SBC running a 1.4GHz Celeron M ULV, and in actual testing outperforms many self-built systems. On the other hand, it also costs over $1000 without drives.ATWindsor - Monday, September 10, 2007 - link
The benches I have seen points to a read-performance of 30 MB/s give or take lets say 10 MB, thats hardly good performance, it doesn't even outperform a single drive. One can easily build a software raid with several times better speed.Gholam - Sunday, September 9, 2007 - link
WHS is made to run on low-power, low-end and old hardware; calculating parity blocks in software is bad enough on a modern desktop CPU, an old PIII/800 or a VIA C3/C7 (present in some OEM WHS box implementations) will get murdered.In addition, recovering data from a failed RAID5 array is quite difficult, requiring specialized (and expensive) software as well as user expertise. Recovering data from a failed WHS box with duplication is as simple as mounting the drives separately.
ATWindsor - Sunday, September 9, 2007 - link
The raid will not fail before two drives goes down, if that happens in WHS, you still need to run recovery-software and hope to get out data. WHS will be run on diffrent kinds of systems, even the cheapest of CPUs today are pretty powerful. More than powerful enough to get reasonable spped on raid5. Why limit WHS in this way? That is exactly the problem I'm adressing, the lack of flexibility, the reasoning that all WHS-users have the same needs, I think a pretty large number of WHS-machines wich poeple build themself will have performance several times higher then a P3@800, if not most.Gholam - Sunday, September 9, 2007 - link
The raid will not fail before two drives goes downOh how I WISH that was true. Let me give you a recent example I've dealt with. HP/Compaq ProLiant ML370G2 with SmartArray something (641? don't remember) running a 4x36 RAID5 array, Novell Netware 5.0. DLT VS80 tape backup drive. Worked for 4 years or so, then the tape died. Took the organization in question 4 months to buy a new one, LTO-2 - which means they've had 4 months without backups. Downed the server, connected the new tape, booted - oops, doesn't boot. Their "IT guy", in his infinite wisdom, connected the tape to the RAID controller, instead of onboard SCSI - which nuked the array. It didn't go anywhere, the controller didn't even report any errors, but NWFS crashed hard. They ended up rolling back to 4 months old backups because pulling data out of a corrupt RAID5 array would've cost several thousands.
I work for a small company that specializes in IT outsourcing for small and medium businesses - basically shops that are too small to afford a dedicated IT department, and we give them the entire solution: hardware, software, installation, integration, advisory, support, etc - and I've got many stories such as this one. We also deal with home users, but not as much.
This said, I don't consider RAID5 a suitable for home use, at least not yet. It's too expensive and dangerous - mirroring files across a bunch of drives is cheaper and easier. Also, as far as I understand, when a drive in WHS drive pool fails, it automatically syncs protected folders into free space on remaining drives, so the window where your data is vulnerable is quite small. RAID5, on the other hand, will be vulnerable until you replace the drive (which can take days or even weeks) and then until it finishes rebuilding (which can also take a very long time on a large array). You can keep a hotspare, but then you'll be eating up another drive - in case of 4 drives, RAID5+hotspare eats you the same 50% as RAID1/RAID10 - while WHS mirroring makes your entire free space function as hot spare.
ATWindsor - Sunday, September 9, 2007 - link
Hardly a very plausible scenario for a home user, of course a RAID can go down if you mess it up, but you can just as easily mess up non-raided drives to the point that running recovery-software is needed, when it comes to normal drive-failiures two of them have to die.If you only need 2 Drives worth of storage, you might as well mirror, but when you need for instance 10, it adds up, but drive-cost, electricity PSU-size and physical size (especially if you want a backuo-machine in adition, I would never keep my data on only one computer like that). If the syncing is going to work,you also need to have at least a disk of usalble free space, so you basically need to "waste" a whole disk on that to if you wnat to get hot-spare-functionality.
Gholam - Monday, September 10, 2007 - link
Hardly a very plausible scenario for a home user, of course a RAID can go down if you mess it up, but you can just as easily mess up non-raided drives to the point that running recovery-software is needed, when it comes to normal drive-failiures two of them have to die.Not quite. WHS balances data between drives, so if one of them becomes corrupt and one of the copies of your protected data is gone, you can still access it on the other - no extra tools required, just mount the drive in a Windows system. You will only lose it if both drives become corrupt simultaneously.
If the syncing is going to work,you also need to have at least a disk of usalble free space, so you basically need to "waste" a whole disk on that to if you wnat to get hot-spare-functionality.
Again, not quite. Since you protect the data on a per-folder basis, your free space requirement depends on the actual amount of data you're keeping redundant, not the total, and there's little point in wasting redundant storage on backups - they're redundancy in and of themselves.