[DRBD-user] Slow Reads on VM - Xenserver and DRBD

Phil Stricker stril at gmx.de
Mon Jul 23 17:52:21 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hi!

I just started with a setup of DRBD and Xenserver 6.0.2

Of course, my read-performance inside the VMs is very bad. The storage system is a Raid 10 with 8x Intel 320 SSD on an LSI-Raid-Controller.

Testing the Read-Performance with hdparm on Dom-0 shows:

/dev/drbd1:
Timing buffered disk reads:  1432 MB in  3.00 seconds = 477.18 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device

If I start the same test in a VM, I get:
Timing buffered disk reads:  100 MB in  2.56 seconds =  39.10 MB/sec


There is just one single VM on that system.


Can you help me? Windows VMs have shown the same issue. The problem does also consist, if the second node is disconnected...

Thank you and best wishes.
Phil



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