SAN Server Specs Question

Posted on 2009-12-28
Last Modified: 2012-05-08
Hi Gurus,

I'm shopping for my first SAN...Essentially, it's a poorman SAN.  The Server I'm looking at is a HP Proliant DL180 G6 and I'm using OpenFiler as the SAN software to use with Vsphere.  

Now my question is, how do I determine how much RAM I'll need on the SAN box and how much RAM will I need on my Vsphere server?  My assumption is that the RAM for the VMs will be allocated from the Vsphere Server and that the RAM on the SAN will be for the SAN Server to do it's own local that correct?

Question by:jetli87
    LVL 8

    Accepted Solution

    Correct! RAM on the SAN box will not be allocated for VMs. It will just be used for running Openfiler, so any more than 4GB won't really help you.

    What kind of VMs will you be running? Storage is really important in any vSphere environment, so I would be wary of running production servers in a SAN environment without good hardware redundancy. If you lose your DL180, all of your VMs will crash simultaneously!


    LVL 42

    Assisted Solution

    You are correct, the resources for the VM come from the ESX host.  

    If you are looking at a lower tier SAN you may want to look at something that is already on the VMware HCL.  I've had a few problems with the DL100 series, HP makes these barebone units and we had about a 30% failure rate within a month.  We are a HP distributor, the DL300 series is much more stable.  

    Here's some units that are in the same ballpark, depending on how many drives you need in the system these are on the VMware HCL or we have used them without any issues for at least a year

    Iomega IX4-200r ISCSI or NFS about $2k

    A used HP MSA2012i - Find on Ebay for under $4K and will have HP NBD onsite warrranty for at least two years left.  Uses SATA drives and you can later add a chasis with sata or sas shelves.  For $4K you should be able to find one with controllers which will give you better failover and HP support if something goes wrong

    My $.02

    LVL 2

    Assisted Solution

    You will need 1 GB of RAM for the ESX vSphere and the remaining ammount will be determined by the total of vm's that you plan to have in there. Remember to have avaiable the ammount of memory requested by the OS. For example if you are going to have a Windows Server 2008 with 4 GB of memory, and another one with 2 GB of RAM make sure you have that same ammount of mem even when they are not going to be used all the time, it is important to have it available.

    On the other hand, I think that 1 GB of ram on the OpenFiler will be more than enough.
    LVL 3

    Assisted Solution

    If you want to build your own using a openfiler SAN then if its a 32 bit openfiler then max it can access will be 4GB. But if you put a 64bit Openfiler then it may see more than 4GB. Mostly the SAN RAM will be used for Write &  Read Caching, and local openfiler processing. And mostly write cache will mostly benefit from huge RAM. For Reading anyway it has to access the hardisk array. I have tried 32 and 64bit OpenFiler long time back and found that 64bit was much more better on same hardware.

    However, if you want to use for production environment then go for Vmware HCL list as mentioned earlier.
    LVL 1

    Author Comment

    hmmm...I checked and the DL180 G6 is on Vmwares HCL.

    Anyways, thanks for the great advise...I've been using ESX on a maxed out ML350 G5 server for our test environment and wanted to extend clustering and such for our Exchange/Sql, and other servers.

    With that, I had a question that I've been curious about, for best practices, in a SAN environment, are all VMs and Vdisk data resided on the SAN or, are VM paritioned OS, i.e. Windows CDrive, resided on the ESX host RAID Array and the VDisk data resided on the SAN RAID Array?
    LVL 42

    Assisted Solution

    The DL180G6 is on the HCL as hardware to install ESX/ESXi not as a NAS/SAN.  

    If you're running ESX host the esxconsole VM is on local storage and the VMs are on the SAN
    LVL 1

    Author Comment

    got it...thanks.


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