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Newbie - concerned over redundancy vs dedicated RAID setup RRS feed

  • Question

  • Hi,
    I currently have a linux based NAS (Buffalo Linkstation Pro) which is rock solid for serving files to a number of home PCs. It also runs a variety of other low-powered/always on tasks such as online backup (rsync/ssh), web serving (apache), snmp monitoring (mrtg), telephony (intended: asterisk), firefly (itunes), twonky (DNLA)

    However with only a single disk I do not have raid protection. I'm looking for some extra safety having being burnt 3 times this year (different systems). I've looked at the ReadyNas Duo (slow, but very automayed), QNAS TS210/219, a custom atom-based PC+enclosure

    Then I saw the HP EX490 which is based on WHS

    At home I have
    * Windows 7 Ultimate x64 desktop (system disk mirrored using dynamic volumes)
    * Windows 7 professional x64 laptop
    * Windows 7 Home premium x64 laptop
    * Windows Xp desktop
    * Windows XP desktop
    * Linux (Fedora 12) laptop << work, don't share many "home" files.

    1. System drive redundancy

    Whilst I can see Home Server offers replication of user data, I couldn't see what the story is with the boot/system drive. I'd like this to be mirrored/protected to offer full redundancy ie system continues running. 

    If this isn't present 24x7 is shot away.

    2. Server/Directory/Replication

    Currently the desktops use folder redirection so that user home is actually on the NAS
    The laptops don't (as they roam) so files are placed manually onto the nas via a mapped drive, or using robocopy/synctoy

    With home server does this become easier/more transparent? Would ideally like all files replicated (accessible from) all systems automatically

    3. Ad-hoc drives

    The system I'm looking at comes with a 1Tb drive. I have a couple of 500/400/300 drives around. I assume I could happily add these to the pool with minimum difficulty. If I then want to expand, and assuming there is enough space in the pool, the server can automatically migrate data off, then on to a larger drive right?
    Wednesday, December 2, 2009 9:51 PM

Answers

  • You're more or less correct with everything, enough so you won't get in any trouble. :)

    Have you looked over the Windows Home Server microsite ? Especially the Help page? You'll find a number of white papers there which discuss various technical aspects of the product in significantly more detail than you can really get here.
    I'm not on the WHS team, I just post a lot. :)
    • Marked as answer by planetf1 Tuesday, December 29, 2009 12:03 PM
    Sunday, December 6, 2009 12:55 PM
    Moderator

All replies

  • I should add my idea of a proper "NAS" is really a full blown SAN with 100s of drives and 4+ Gbps redundant switched networks... I'm trying to "downsize" that idea onto something my monthly pay cheque can stomach.....

    Just on the boot drive issue -- I don't see "restore" as a viable option. So can dynamic volumes be used for sw raid?
    Final note - more a *nix expert than a Win expert...
    Wednesday, December 2, 2009 9:52 PM
  • To answer your questions in order:

    1. There's no redundancy for the system drive. The product is designed to be used/maintained by a non-technical person, so I suppose that Microsoft felt that adding redundancy (RAID, etc) would be too confusing. They went to a lot of trouble to simplify the user interface as much as possible. The designed response to a failed system drive is replacement of the drive, followed by a server recovery process which will reintegrate the storage pool drives with the server, but this doesn't preserve data stored on the system drive.
    2. Redirection of folders onto Windows Home Server (along with offline files, I assume?) isn't really recommended, because some applications don't deal well with the way Drive Extender handles files behind the scenes.
    3. Yes. When you add a drive to the storage pool, Windows Home Server will format it and add it to server storage. When you remove a drive from the pool, it will move any files stored on the drive to other drives still in the pool, if there's room. If there isn't, it will warn you of the fact.
    4. Software RAID, dynamic disks, etc.: Not supported. Dynamic disks can cause data corruption. Hardware RAID is also not supported, for reasons of simplicity and cost, but it's possible to use a RAID array with Windows Home Server.

    I would suggest you look into the information and documentation available on the Windows Home Server microsite, especially the support page, which has links to a number of white papers on the various functions Windows Home Server can perform.


    I'm not on the WHS team, I just post a lot. :)
    Wednesday, December 2, 2009 10:21 PM
    Moderator
  • Thanks for the reply.

    I do like the flexible storage pool as indicated in #3 above, but *for me* the r'aison d'etre really is for a fault tolerant storage system. WHS will not deliver this without redundancy for the boot/system drive. The extra capability/power is great, but above all else I want that storage to just be there, to be available, without having grief from my kid/wife one night when the system drive has failed. I already have plenty of backups (both to USB storage and remote site, with a lag of minutes to a day) with my current single-disk nas. Now I want availability (not that I've had issues thus far, I just know it will happen some day)That does not to me mean reinstalling the system image from backup

    What was a little surprising was to see the comparison of raid vs this more flexible pool management -- arguing this as a reason to go WHS. And of course it is far more flexible than the entry level raid systems on the market.., but not mentioning this limitation.

    Out of interest on #4, why would dynamic disks cause data corruption? I just ask since I'm using them on one of the W7 PCs... this logical volume capability has been a std part of windows for years?

    so perhaps a more appropriate view is that this is indeed offering good "server" capability ie on conjunction with a raid array, but it's not completely replacing raid with that limitation in place.

    Kinda still hoping I'm wrong and there's some neat workaround.... or maybe I'm being a bit harsh on the restore process.. but look at those basic hw raid devices. A failed disk is alerted, can be swapped out, replaced, it gets reintegrated with no more than a flashing led/email and a disk re-insertion process. Now that IS simple for the end user. no Gui or anything.
    Thursday, December 3, 2009 1:14 AM
  • Dynamic disks: here's the KB article that describes the issue. I can't tell you for sure, but I doubt that it has been fixed in Power Pack 3 since there is no supported way to change a disk in your server from basic to dynamic.

    As far as reliability/availability goes, my production server has been running since November of 2007, with no crashes, no errors, etc. 'Nuff said? :) I've had to do numerous recoveries on my lab server (of course), and it's not as bad as you think. You just have to accept the basic premise that the solution tree for most problems only has one supported branch, and it's labeled "server recovery".

    As for the rest, well, Windows Home Server isn't designed for the IT pro, for the most part. It's designed for someone with little technical knowledge, but a realization that there's a lot of data in his or her home that needs better protection than keeping it on "the family room PC" really gives. Look at RAID from that viewpoint, and you'll understand why it's not a part of the product's vision. Also, the cost for a really good RAID card is pretty high, it really needs additional hardware to shine, and you would start off with several disks in your server. Factor in the fact that a dollar in parts for the OEM (bill of materials or BOM cost) can equal three or four dollars on the sticker, and RAID could easily double or triple the price of an entry level OEM server. Nobody would buy the OEM servers at that point, and that's most of the sales.


    I'm not on the WHS team, I just post a lot. :)
    Thursday, December 3, 2009 2:33 PM
    Moderator
  • I must echo planetf1's concerns regarding the lack of redundancy of the system drive.  I love everything about WHS, which I use as a SageTV server, with one exception - the lack of a decent redundancy and backup of the system drive.  Having to reinstall is to much of a pain, especially if you run other apps and have to reinstall drivers, etc. 

    I really wish MS would get their act together - having a mirrored system drive would be great where the server would switch over from one disk to another if bootup failed.   If I remember correctly that is similar to how a TiVo (at least Series 1) worked to make it fault tolerant - the (linux) OS was installed on two separate partitions, albeit on the same drive to give you a measure of redundancy as they want it to act more like a Consumer Electronics device than a PC.
    Thursday, December 3, 2009 10:40 PM
  • WHS will not deliver this without redundancy for the boot/system drive.

    In the officially supported mode, this statement is very true.  For those of yes that value our time with 12 TB of data, we use the not supported mode of running the boot/system drive in RAID 1 and set-up the data drives with duplication turned on.  My only suggestion for anyone thinking about doing this is spend the money for a quality RAID card and do not use what's built in the motherboard for any type of RAID.
    Thursday, December 3, 2009 11:12 PM
  • One other thought.

    My NAS is currently backed up offsite via rsync.
    I'd like to backup WHS managed data (video, photos) via rsync/ssh. Presumably this is just a case of
     a) getting hold of an rsync port
     b) running the rsync against a share

    details like filename case significance, and finding a plugin/port I'm sure can be sorted

    I'd guess/hope either Unix System Services or cygwin would be sufficient?
    Sunday, December 6, 2009 2:07 AM
  • You can try it. I don't guarantee it will work, however. At worst, you will not be able to bak up using rsync, so you'll have to fall back to something like robocopy or even Windows Home Server's built-in server share backup feature (which copies to a disk connected and added to the server as a backup disk).
    I'm not on the WHS team, I just post a lot. :)
    Sunday, December 6, 2009 4:27 AM
    Moderator
  • Given my lack of knowledge in windows server (. background is *nix) .... you might also be able to tell I'm an architect so I'm doing a bit of architecting before launching into implementation ;-). I use all kinds of OSs/hypervisors from embedded OS to mainframe just right tool for the job at hand....


    I'm thinking about how WHS manages it's replicated storage. If I'm not mistaken you basically see a NTFS filesystem in each disk. Some of the files/dirs on that disk may be links/reparse points? And somehow between all the disks there will be >1 copy of each file (if selected). WHS will migrate data between disks as it sees fit.

    So basically trying to backup the ntfs filesystem is non-sensical.

    However WHS clearly presents a unified logical view of this data through the SMB shares it exports

    Presumably this means that any applications running locally on WHS that want to use music, photo data in these replicated stores needs to refer to that as \\server\music or \\server\johnsmith instead of d:\data\music etc?

    So from this I'd conclude that for any rsync etc job
     * It would be best to install cygwin (I think SFU is rather outdated now?) in one of these replicated stores - this is just to avoid re-install etc if system disk fails
     * The ssh/rsync job needs to refer to data from \\server\music (ie UNC path) [cygwin does support UNC]
     * WHS is case-preserving, but case-insensitive. This is the same as my existing NAS (samba options set to defaults). So I don't think I'll have issues with names. (some NAS's do very strange things including some synology's which hacked ext3. not mine. Ouch.)
    Sunday, December 6, 2009 11:11 AM
  • Just realised I also need to check how cygwin itself handles case sensitivity.
    Sunday, December 6, 2009 11:14 AM
  • You're more or less correct with everything, enough so you won't get in any trouble. :)

    Have you looked over the Windows Home Server microsite ? Especially the Help page? You'll find a number of white papers there which discuss various technical aspects of the product in significantly more detail than you can really get here.
    I'm not on the WHS team, I just post a lot. :)
    • Marked as answer by planetf1 Tuesday, December 29, 2009 12:03 PM
    Sunday, December 6, 2009 12:55 PM
    Moderator