Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello,
I have a backup time degradation problem.
In a nutshell (it looks a write latency performance):
- the old IO pair ( SLES10 + drbd 8.2.6 ) can finish the task in 10 seconds
- the new IO pair ( SLES11SP2 + drbd 8.3.12 ) can do it in 16 seconds only.
I can force the old 8.2.6 configuration to slow down if I comment
out
no-disk-flushes ;
no-md-flushes ;
from the disk section in the config file.
When I change the 8.3.12 configuration, it has no effect on speed.
I can prove this "slow down" with the 'standard' drbd latency measurement command:
dd if=/dev/zero of=/opt/mirror/perftest/sles.latency-bs512-count4096 bs=512 count=4096 oflag=direct
In this special case the new system is 4 times slower!
Questions:
A) - Is it a known issue for the 8.3.12 drbd ? ( no-disk-flushes no-md-flushes has no real effect )
B) - I have checked the sysctl and io-scheduler settings and tried to
tune the SLES IO performance with no success.
// I used :
http://www.suse.com/documentation/sles11/pdfdoc/book_sle_tuning/book_sle_tuning.pdf
// and alsohttp://www.drbd.org/users-guide/s-throughput-tuning.html
Is there any hint to try?
I must admit that the throughput test shows 20% advantage,
but I do not mind if it becomes worse, if I can tune up the latency.
Thanks your help in advanced:
BR,
Akos
Here is my config if anyone need it
-----------------------------------------------
drbd IO configuration on a SLES10 installation:
-----------------------------------------------
# drbdsetup /dev/drbd0 show
disk {
size 0s _is_default; # bytes
on-io-error detach;
fencing dont-care _is_default;
no-disk-flushes ;
no-md-flushes ;
max-bio-bvecs 0 _is_default;
}
net {
timeout 60 _is_default; # 1/10 seconds
max-epoch-size 2048 _is_default;
max-buffers 2048 _is_default;
unplug-watermark 128 _is_default;
connect-int 10 _is_default; # seconds
ping-int 10 _is_default; # seconds
sndbuf-size 131070 _is_default; # bytes
ko-count 0 _is_default;
after-sb-0pri discard-least-changes;
after-sb-1pri violently-as0p;
after-sb-2pri violently-as0p;
rr-conflict disconnect _is_default;
ping-timeout 5 _is_default; # 1/10 seconds
}
syncer {
rate 12288k; # bytes/second
after -1 _is_default;
al-extents 127 _is_default;
verify-alg "";
}
protocol C;
_this_host {
device "/dev/drbd0";
disk "/dev/part4";
meta-disk internal;
address 172.16.32.13:7788;
}
_remote_host {
address 172.16.32.9:7788;
}
---------------------------------------------------
drbd IO configuration on a SLES11_SP2 installation:
---------------------------------------------------
# drbdsetup /dev/drbd0 show
disk {
size 0s _is_default; # bytes
on-io-error detach;
fencing dont-care _is_default;
no-disk-flushes ;
no-md-flushes ;
max-bio-bvecs 0 _is_default;
disk-timeout 0 _is_default; # 1/10 seconds
}
net {
timeout 60 _is_default; # 1/10 seconds
max-epoch-size 2048 _is_default;
max-buffers 2048 _is_default;
unplug-watermark 128 _is_default;
connect-int 10 _is_default; # seconds
ping-int 10 _is_default; # seconds
sndbuf-size 0 _is_default; # bytes
rcvbuf-size 0 _is_default; # bytes
ko-count 0 _is_default;
after-sb-0pri discard-least-changes;
after-sb-1pri violently-as0p;
after-sb-2pri violently-as0p;
rr-conflict disconnect _is_default;
ping-timeout 5 _is_default; # 1/10 seconds
on-congestion block _is_default;
congestion-fill 0s _is_default; # byte
congestion-extents 127 _is_default;
}
syncer {
rate 12288k; # bytes/second
after -1 _is_default;
al-extents 127 _is_default;
on-no-data-accessible io-error _is_default;
c-plan-ahead 0 _is_default; # 1/10 seconds
c-delay-target 10 _is_default; # 1/10 seconds
c-fill-target 0s _is_default; # bytes
c-max-rate 102400k _is_default; # bytes/second
c-min-rate 4096k _is_default; # bytes/second
}
protocol C;
_this_host {
device minor 0;
disk "/dev/part4";
meta-disk internal;
address ipv4 172.16.0.13:7788;
}
_remote_host {
address ipv4 172.16.0.9:7788;
}
--
This communication is confidential and intended solely for the addressee(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you believe this message has been sent to you in error, please notify the sender by replying to this transmission and delete the message without disclosing it. Thank you.
E-mail including attachments is susceptible to data corruption, interception, unauthorized amendment, tampering and viruses, and we only send and receive emails on the basis that we are not liable for any such corruption, interception, amendment, tampering or viruses or any consequences thereof.
Ericsson Magyarország Kft., Székhely: 1097 Budapest, Könyves Kálmán krt. 11. B. épület. Nyilvántartó cégbíróság: Fõvárosi Bíróság. Cégjegyzékszám: 01-09-070937