On a legacy project I've got 4 physical machines (servers, PM's) where each server has access to the SAN and fixed-space by it's own two devices (via device-mapper multipath). The local disks of the servers are rather small but fast and capable of storing virtual machines.

Do you have suggestions of how to utilize the storage space the physical machines (hosts) can access for the virtual machines (guests)? (The SAN itself does not offer I-SCSI or NFS access)

Ideally I would implement some kind of shared storage between some of the VM's that can be used in both a webserver and a database scenario. The architecture or server setup should allow maintenance or failure of a physical machine.

I'm interested in basic tips, recommendations, do's and dont's (OCFS2, DRBD, ...).

I'm aware my description is far from detailed. Feel free to ask.

  • I don't know if KVM supports it, but a SAS SAN might work in your case. Just need to buy/install a SAS Switch between the servers and DAS. I know it works for Hyper-V and ESX. – Chris S Mar 29 '11 at 12:43

You'll get a lot more benefit in the long term from implementing a proper shared storage solution, but there's lots of virtual appliances that will implement sharing (either by NFS or iSCSI) of local storage. The obvious ones to look at are Openfiler and FreeNAS, which both do the job well.

However, it sounds more like you're trying to implement clustered network storage with live mirrors of the data on each server? There's lots of details on how to do this with Xen and OCFS2 here, but honestly, if your data is worth anything, and you ever want someone other than yourself to maintain the system, don't do it.

Better to stick the VMs on real shared storage, it doesn't have to be hugely fast, expensive or even new, but it'll be an awful lot less hassle.

  • 1
    Ewan, thanks so far for your answer. I can't setup shared storage, well, I can, but I don't want to dedicate one of the PM's to be a fileserver. Currently I'm looking more into DRBD, LVM and smth. like Proxmox as you guess in your second paragraph. – initall Apr 8 '11 at 17:55
  • Well, good luck is all I can say - I've tried DRDB before without enough success to run it in production, but perhaps it's improved. – Ewan Leith Apr 11 '11 at 12:09

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