On Mon, Mar 15, 2010 at 10:41 AM, Amos Shapira <amos.shap...@gmail.com>wrote:
> 2010/3/12 Hetz Ben Hamo <het...@gmail.com>: > > Hi, > > I have taken 3 machines for a project: 2 machines will act as Xen servers > > and one machine will act as "storage". > > The storage box is just a machine with few hard disks connected with a > RAID > > controller. > > What I would like to do is create few Xen VM's with the fastest possible > I/O > > in terms of storage. > > I have few options: > > 1. I can create an LVM on the storage machine, create few Logical Volumes > > and export them as NFS to the Xen servers and configure each VM to some > file > > images. Problem is, that file I/O with Xen is slower compared working > with > > LVM's. > > 2. I can create an LVM on the storage machine, create few Logical > Volumes, > > and export those as iSCSI devices. I'm not sure whats the performance of > Xen > > with iSCSI devices exported from the storage box. > > 3. I can create few partitions on the storage machine, export them as > iSCSI > > devices and do LVM on the Xen servers. Problem: I don't know how much the > > "penalty" doing LVM on the Xen machines. > > My question: What is the best option? > > Thanks, > > Hetz > > I don't have practical experience with hosting Xen images on SAN but > when I researched the market for a SAN-based configuration of our > production network (currently 20 Xen hosts hosting about 10 Xen guests > each, doing DRBD between pairs of Xen guests and linux-ha for HA), at > least one or two of the options I checked mentioned that if I store > the Xen images on the SAN then it will require much higher bandwidth > to it than if I use it just for plain data. > Why? Where does the secret IO arrive from? Ez > > Based on this input, I'd recommend that you'll look at having the > images on internal server disks and try to achieve HA at the xen guest > level, then compare the performance with iSCSI hosted xen images. > > Hope this helps. > > --Amos > > _______________________________________________ > Linux-il mailing list > Linux-il@cs.huji.ac.il > http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il >
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