<div dir="ltr"><br><br><div class="gmail_quote">On Mon, Mar 15, 2010 at 10:41 AM, Amos Shapira <span dir="ltr"><<a href="mailto:amos.shapira@gmail.com">amos.shapira@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
2010/3/12 Hetz Ben Hamo <<a href="mailto:hetzbh@gmail.com">hetzbh@gmail.com</a>>:<br>
<div><div></div><div class="h5">> Hi,<br>
> I have taken 3 machines for a project: 2 machines will act as Xen servers<br>
> and one machine will act as "storage".<br>
> The storage box is just a machine with few hard disks connected with a RAID<br>
> controller.<br>
> What I would like to do is create few Xen VM's with the fastest possible I/O<br>
> in terms of storage.<br>
> I have few options:<br>
> 1. I can create an LVM on the storage machine, create few Logical Volumes<br>
> and export them as NFS to the Xen servers and configure each VM to some file<br>
> images. Problem is, that file I/O with Xen is slower compared working with<br>
> LVM's.<br>
> 2. I can create an LVM on the storage machine, create few Logical Volumes,<br>
> and export those as iSCSI devices. I'm not sure whats the performance of Xen<br>
> with iSCSI devices exported from the storage box.<br>
> 3. I can create few partitions on the storage machine, export them as iSCSI<br>
> devices and do LVM on the Xen servers. Problem: I don't know how much the<br>
> "penalty" doing LVM on the Xen machines.<br>
> My question: What is the best option?<br>
> Thanks,<br>
> Hetz<br>
<br>
</div></div>I don't have practical experience with hosting Xen images on SAN but<br>
when I researched the market for a SAN-based configuration of our<br>
production network (currently 20 Xen hosts hosting about 10 Xen guests<br>
each, doing DRBD between pairs of Xen guests and linux-ha for HA), at<br>
least one or two of the options I checked mentioned that if I store<br>
the Xen images on the SAN then it will require much higher bandwidth<br>
to it than if I use it just for plain data.<br></blockquote><div><br></div><div>Why? Where does the secret IO arrive from?</div><div><br></div><div>Ez</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>
Based on this input, I'd recommend that you'll look at having the<br>
images on internal server disks and try to achieve HA at the xen guest<br>
level, then compare the performance with iSCSI hosted xen images.<br>
<br>
Hope this helps.<br>
<font color="#888888"><br>
--Amos<br>
</font><div><div></div><div class="h5"><br>
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