Den 26/04/2012 kl. 13.02 skrev Tracy Reed: >>> >>> 1. Disk alignment between Xen VMs and the target. >> >> What do you mean by that? > > I mean that when I configure a Xen VM to use an AoE block device I always had > mis-aligned writes. The Xen dom0 has the block device in /dev/etherd and I put > the block device in the Xen VM config file and make it /dev/xvda inside the > VM. > > If I access the device from dom0 everything is fine. Very fast writes, no > misalignment. But accessing the block device from within the VM causes the > problem. This makes no sense to me and I don't see anything that could cause > alignment to change but it clearly did somehow. This got to be very noticeable > performance-wise and when doing a pure-write benchmark while running iostat on > the target I could see lots of reads happening to backfill partial pages due > to > the misaligned write.
FYI: Using XenServer 5.6 SP2 with AoE-targets (both coraid appliances and ggaoed) I get the same diskspeeds in XenServer dom0 and VM domU. So /Lars ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Aoetools-discuss mailing list Aoetools-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aoetools-discuss
