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Thread: NAS and SAN for storage

  1. #1
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    Default NAS and SAN for storage

    I'm looking to deploy Zimbra but we're an all NAS (Network Attached Storage) shop. Will Zimbra work with a NAS backend (network share) for storage or will it be a lot better to look at DAS or SAN (block storage) for our deployment...

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    Welcome.

    DAS or SAN for sure.
    However, it depends on the usual answers : how many users, how many active users, how many mails, how much quota (if quota), etc

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    I've been told that Zimbra was not NAS friendly or that NAS was not supported at all. It sounds like it will work off of a NAS back end.

    I'm not worried about the scaling issues that you mentioned as long as Zimbra will scale on NAs as well as it does on any other platform. Our NAS system is almost 1PB and can sustain well over 2GB/s (as in 2000MB/s). We have GigE as well as 10GigE connections to various switches/servers at our disposal - all with low latency even when compared to DAS or SANs...

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    So, just to be clear when we say "NAS" we mean mounting a network file system like CIFS or NFS, and when we say "DAS" (or DASD in IBM-speak) or "SAN" we are talking about mounting a block storage device, yes?

    If so, you will be much better off with block storage for the Zimbra directories likely to consume the greatest space and/or I/O.

    We have tried NFS but have not found it reliable; CIFS doesn't support hardlinks and is slow.

    Hope that helps,
    Mark

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    Yes...
    NAS - Network attached storage (SMB, NFS)
    DAS - Direct Attached Storage (drives in servers)
    SAN - Storage Area Network - storage arrays presenting block LUNs via fibre channel network

    Thanks for the info. Do you know of any plans to improve Zimbra performance and reliability when using NFS or SMB (CIFS) NAS shares? Also, I take it from your response that Zimbra does officially support share mounted backend storage...

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    I think the issue with Zimbra and NAS has less to do with Zimbra and more with the components underlying Zimbra. CIFS doesn't support hardlinks for example, and running MySQL databases on NFS mount points can bork the databases when NFS goes wonky. And to be fair, even a really stable NFS system is noticeably slower than a SAN or DASD.

    I don't believe Zimbra officially supports network file systems BTW, though a number of folks on the forums report success with things like /opt/zimbra/backup on NFS.

    FWIW, we don't use any network file systems with Zimbra, just DASD and SANs.

    Hope that helps,
    Mark

    P.S. Cheap DASD these days for HP servers is a used MSA30 disk shelf (about $200 or so) loaded up with used 146GB or 300GB drives.

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    NFS works so bad that the install script refuses to install ZCS if it find NFS mounts (as ZCS' volumes)...

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    Thanks for the info, I think I have what I need. Since we're only a NAS shop this will have to go into our decision on whether or not to move.

    Just to dispel a common myth, NAS is not slower than a SAN. SANs are not purchased for speed (which is another myth). DAS is almost always faster than SAN or NAS unless the NAS or SAN was specifically built for speed. In our case we run Bluearc NAS which is fairly expensive but is also easily several times faster than any SAN on the market and faster even than a well built DAS RAID system. Plus, of course, it scales to PetaBytes easily and performance scales almost linearly - something that is impossible with a single server and DAS and the HP MSA stuff as well.

    NFS is not wonky at all although largely misunderstood by many. SMB2 is rock solid as is SMB1 as long as you understand it's limitations. Because of the performance and reliability of our NAS system we may still try Zimbra - but it would have to be on NAS. Our mail system is far too big for the low end stuff from HP or DAS - did I mention we have a full PB of NAS on one system and growing?...:-)

    Thanks again for the help and quick responses...

    Our NAS syste

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    I have been using NFS for zimbra for quite a while and have had no issues related to NFS. We use a NetApp storage system for NFS and CIFS. You can't beat the backup capabilities. The Snapshots have saved me multiple times and allowed me to test new versions easily.

    I have tried iSCSI with the NetApp as well for Zimbra. I saw no benefit to that so stayed with NFS.

    The only inconvenience I see with NFS is that Zimbra complains that "Disk space is below threshold" for various Zimbra directories. It seems that the startup script is issuing df commands and not recognizing the NFS mount.

    I do use gigabit ethernet and would not recommend NFS without GigE.

    -tom

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    We have clients who even run MySQL databases on v3 NFS mounts with no problems, so we don't discount NFS as a matter of course.

    Having the NFS share provided by good hardware/software, like a NetApp, of course helps.

    It's just that NFS doesn't work reliably enough for us (and apparently for Zimbra) to spend billable client time trying to get it to work when we have other more reliable same-cost options available.

    Clearly this is one case where the phrase "YMMV" definitely applies!

    All the best,
    Mark

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