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, Cont
As for restoring data, WHS comes with two options. The first is the traditional per-file restore, which can only be handled by a client. When a user/client wants to restore a file, they will pick the date/backup from which they want to restore the file, at which point the connector software will mount a dynamically-generated volume that is the contents of the client as of that backup. At this point the user can copy over files from the backup volume to their hard drive.
For a more complete restore, such as in the case of a catastrophic failure or those looking to use WHS as an image backup server, WHS ships with a live-restore CD. When the restore CD is inserted into a computer, the affected machine can connect to the WHS server and select a whole backup to restore. Since the operating system is included in the backup, it is also included in the restore, returning the machine to the same state it was in as of the backup. This process does however wipe the client's hard drive in the process, so it's not something that can be used leisurely. Power users that will be using it as a way to image and restore machines will especially appreciate the ability to restore to volumes of arbitrary size, and while Microsoft isn't pushing the imaging ability hard, it's one the best features of WHS.
There are a few caveats with the backup features of WHS that bear mentioning however. First and foremost only machines running Windows XP SP2 or Windows Vista x86 can be backed up. Older versions of Windows are not supported, and more surprisingly x64 versions of Windows are not supported. The WHS development team has cited the need to write drivers for the backup/restore abilities as the reason for the latter limitation, as they did not have the time to write a good set of drivers for both x86 and x64, so x64 support is not included for now. Unfortunately we don't have a good idea when such support will arrive; the development team for WHS is working on writing a version of the software for x64, but they are not saying when it might be ready.
Hardware constraints also need to be considered. Backups are transfer intensive, so anything less than a gigabit Ethernet link will cause the network to be the bottleneck. This is especially problematic for wireless links, which under 802.11g are practically capped to less than 6MB/sec (and realistically top out at under 4MB/sec), a fraction of the transfer rate of a hard drive. Microsoft highly recommends at least a 100Mb Ethernet link (forgoing a recommendation for wireless entirely), but wireless will work at the cost of being especially slow when WHS needs to do another full backup because it is ready to throw out the old one.
Last, there is the issue of doing backups at convenient times. A machine needs to be fully-on to be backed up, and WHS only has a limited ability to deal with AWOL machines and deal with machines that aren't currently on; it (or rather the connector) can wake up sleeping computers, but does not have a wake-on-LAN feature for waking up computers that are shut off entirely. An add-on exists that can handle this, but the only reliable way of backing up a machine at night is to leave it on or put it to sleep instead of turning it off. Sleeping however can be more problematic on an enthusiast computer than an OEM-built one.
With that said, it's very clear that Microsoft has put a lot of thought and their best technologies into the backup feature of WHS. Although this isn't a round up where we can adequately and fairly compare all the major backup software suites, we will say that we're very impressed with what WHS can do here. The backup features alone can sell WHS if the price is right as is the number of machines.
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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.