Hi again,
This is the issue with synchronization PV.
We tried to setup this according to the following guide.
http://www.drbd.org/users-guide/s-lvm-drbd-as-pv.html
DRBD version 8.3.10
OS version RHEL5.2
kernel version 2.6.18-92.EL5 (x86_64）
LVM version LVM2(included in RHEL 5.2)
Hardware information;
I/O scheduler: deadline
partition size: 100GB
CPU: 6 core x 2
Memory: 12GiB
HDD: SAS 10000rpm, 300GiB
DRBD works well, but there are a perfomance problem.
We run "dd" like thie;
# dd if=/dev/zero of=/mnt/dd/10GB.dat bs=1M count=10000 oflag=direct
then, "iostat" shows the strange output.
# iostat -xmd 10 /dev/cciss/c0d3
-------------------------------------------
| wMB/s | w/s
-------------------------------------------
hdd | 68.6 | 805
drbd | 47.3 | 910
lvm on drbd | 31.8 | 8140
-------------------------------------------
In case of "lvm on drbd", w/s shows relatively large value compared to
other cases,
nevertheless I/O is not so busy, CPU %util increase to 100%.
so DRBD sync performance drops significantly.
there is no I/O error but Pacemaker detects it as DRBD's error(monitor
Timed out).
We also tried the same test on RHEL 5.5 and RHEL 6.1,
but the result is the same.
Have anyone ever seen a similar problem?
LVM2 included in RHEL 5.2 might be too old, but RHEL 6.1 is the same,
is there some tips for physical volume settings?
Best Regards,
Junko IKEDA
NTT DATA INTELLILINK CORPORATION
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