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Thread: Creating a "mini SAN"... will work with Zimbra?

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    Default Creating a "mini SAN"... will work with Zimbra?

    Hi everyone

    I'm looking to start doing to test migrations from MS SBS 2003 to Zimbra and for my test installations I was thinking of creating a sort of "mini SAN"

    I'd like to add a couple of drives to our existing NAS RAID card (3Ware 9690SA-8i) on one machine and have another machine to host my test Zimbra installation.
    This box will eventually have 15-20 users.

    1) So if I export a 500GB unit (2x500GB in a RAID 1) as NFS from our storage box, and mount it on the Zimbra machine will that perform ok?

    I'm planning to connect the 2 boxes through a dedicated VLAN on our Netgear L2 switch (GSM7224), both connected over a dynamic 802.3ad LACP bonded link so that should give 2Gbps between the boxes.
    2) That should be more than enough bandwidth for our relatively slow 7200rpm SATA drives right?
    I'm assuming the writing/reading the data on the actual disks will be the bottleneck in all this, not the network.

    3) Also I've read many articles on here with people talking about SAN storage and I guess the only way they connect storage to the Zimbra box is through gigabit ethernet connections?

    4) My main concern is latency... will doing this give me some horrible latency since all packets will have to fly through the switch rather than just going to a RAID card connected to the motherboard.
    If latency was a problem though I assume noone would use a "SAN" method... but thought I would check on here first.
    Since the zimbra box will be constantly accessing big mysql db files and all the binary attachment blob files I thought latency could be a problem.

    5) If I do this, how strongly should I consider RAID 10 over RAID 1?
    I'd have to change our NAS from a RAID 6 to a RAID 5 to give me 4 spare drive bays for a RAID 10

    Mainly I'm looking at this as an experiment, since I've never messed around with NFS exporting and creating VLANs on our switch before.
    But if you all think this is never going to work then I'll go for local storage instead.
    So I'd appreciate some answers to my Qs and any other comments/suggestions anyone might have!

    Cheers, B
    Last edited by batfastad; 09-21-2009 at 01:28 AM. Reason: Typo

  2. #2
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    Quote Originally Posted by batfastad View Post
    Hi everyone

    I'm looking to start doing to test migrations from MS SBS 2003 to Zimbra and for my test installations I was thinking of creating a sort of "mini SAN"

    I'd like to add a couple of drives to our existing NAS RAID card (3Ware 9690SA-8i) on one machine and have another machine to host my test Zimbra installation.
    This box will eventually have 15-20 users.

    1) So if I export a 500GB unit (2x500GB in a RAID 1) as NFS from our storage box, and mount it on the Zimbra machine will that perform ok?
    Any use of SMB or NFS for a Zimbra Server (for Store, mysql, index, other important data) is highly discouraged. It might be working for 15 or 20 users, but my recommendation is: don't do it!

    I'm planning to connect the 2 boxes through a dedicated VLAN on our Netgear L2 switch (GSM7224), both connected over a dynamic 802.3ad LACP bonded link so that should give 2Gbps between the boxes.
    2) That should be more than enough bandwidth for our relatively slow 7200rpm SATA drives right?
    I'm assuming the writing/reading the data on the actual disks will be the bottleneck in all this, not the network.
    Network speed is not the bottleneck.

    3) Also I've read many articles on here with people talking about SAN storage and I guess the only way they connect storage to the Zimbra box is through gigabit ethernet connections?
    SAN is fibrechannel or iSCSI (iSCSI preferably over Gig Ethernet). What you are talking about is NAS.

    4) My main concern is latency... will doing this give me some horrible latency since all packets will have to fly through the switch rather than just going to a RAID card connected to the motherboard.
    If latency was a problem though I assume noone would use a "SAN" method... but thought I would check on here first.
    Since the zimbra box will be constantly accessing big mysql db files and all the binary attachment blob files I thought latency could be a problem.
    Latency that is introduced through a Ethernet Switch is negligible. The bad performance of NFS or SMB is not in any way related to network latency but to the protocol itself.

    5) If I do this, how strongly should I consider RAID 10 over RAID 1?
    I'd have to change our NAS from a RAID 6 to a RAID 5 to give me 4 spare drive bays for a RAID 10
    RAID 10 is always better than RAID1,5 or 6.

    Mainly I'm looking at this as an experiment, since I've never messed around with NFS exporting and creating VLANs on our switch before.
    But if you all think this is never going to work then I'll go for local storage instead.
    So I'd appreciate some answers to my Qs and any other comments/suggestions anyone might have!

    Cheers, B
    There is no problem with a VLAN setup. But don't use NFS or SMB/Samba. An iSCSI approach is much better...

    Regards
    Thomas

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    Ok perfect. Thanks for the clarification on NFS, I won't go near it with a bargepole!
    Just been looking into iSCSI and it looks like a great way to do it.

    So how does this sound?
    A pair of 7200rpm SATA drives in a RAID 1 using iSCSI over a 2x1gbps bonded ethernet (802.3ad dynamic with LACP) connection on a dedicated VLAN in our switch.

    I'd love to go with RAID 10, but our shared files system is RAID 6 and using 5 of the 8 available drive slots in the backplane already.
    If we stepped this down to RAID 5 we would have 4 spare to have Zimbra on a RAID 10 but then I lose the ability to have a hot-spare drive.
    I'll definitely consider this though.

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    That's all good, but what are you trying to accomplish by doing this? Is this a test / experiment or is this something you are actually planning on using for production?

    Maybe I'm missing something (and please.. let me know if I am) but the times we use SAN for storage is when we need it for something like Veritas CFS / RedHat GFS or when a HA cluster needs access to shared storage. What advantage do you gain by having two servers - one holds the disks and another has the app (zimbra in this case) over putting a RAID card in the zimbra server and keeping the storage all local? Before I get attacked for being mean, that's not my intention.. I really am curious as to why SAN is a good choice in this specific setup. On the surface, it increases the single points of failure and adds what appears to be unneeded complexity to the setup.

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    No that's a fair enough question and I completely understand its adding many more levels of complexity/failure.

    The reason I was even looking into this was because I'm looking to virtualise Zimbra.
    Upgrading an existing server (currently acting as the NAS/intranet box described below) to 8GB memory and a quad core Xeon so it can run 2 VMs:
    - Our production Zimbra server
    - Our shared files/intranet DB box (apache/mysql/samba/netatalk)

    When I started looking into VMware Server I was concerned about the I/O overhead when accessing the storage through SCSI passthrough.
    I didn't want to just be creating 1TB VMware virtual disk files either... don't like the idea of having all our data stored in one massive image file like that.
    So I thought about using ESXi instead but then I can't install the 3Ware 3DM2 monitoring/tuning service on the host OS.

    So a separate low-power "SAN" box (running the 3Ware 3DM2 service) for the storage and the beast box for ESXi seemed like the best option.
    Plus it's a cool test exercise.

    However I've now been looking into OpenVZ which would allow me to run the 3Ware 3DM2 service on the host, and the "VMs/containers" would be perfectly happy accessing the local RAID card storage.
    Last edited by batfastad; 09-21-2009 at 09:51 AM.

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