Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Tue, 24 Jul 2012 09:40:17 +0200 Felix Frank wrote: > On 07/24/2012 06:14 AM, Christian Balzer wrote: > >> > Can you help me? Windows VMs have shown the same issue. > > That clearly looks like some Xen deficiency or configuration issue, > > can't help you with that, sorry. > > > > That reminds me - I've once heard a talk on just why Xen has I/O > performance issues. It's because of the way syscalls are handled among > DomU kernel, Dom0 kernel and hypervisor. > Yeah, I've read the same thing and am leaning towards KVM for a fully virtualized system, though Vserver and (in the future) LXC work for 90% of the requirements I have. [...] > > Finally: hdparm? Isn't that limited to the old IDE kernel drivers? Are > you using those? If so - why? > While I certainly wouldn't recommend hdparm as generic storage and filesystem performance measuring tool (bonnie++ comes to mind), it does the "right" thing for read tests, more or less. --- # hdparm -t /dev/drbd0 /dev/drbd0: Timing buffered disk reads: 2114 MB in 3.01 seconds = 702.38 MB/sec --- That clocks in about 15% (100MB/s) slower than my bonnie tests, but it's at least in the same ballpark. So the numbers he's seeing are unfortunately correct AFAICT. Regards, Christian -- Christian Balzer Network/Systems Engineer chibi at gol.com Global OnLine Japan/Fusion Communications http://www.gol.com/