Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
All,
I'm setting up a drbd setup for my system, but the poor disk write
performance is really throttling my system, even with Protocol A. The write
speed needs to be 20MB/s to not bottleneck my system. Anyone has advice
tuning for small writes? 10kb writes is the most common operations my
system does.
It doesn't make much sense to me Protocol A performance is so much off
native. Anyone has a theory?
# for i in $(seq 5); do dd if=/dev/zero of=/dev/drbd1 bs=10K count=1000
oflag=direct; done
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 8.43085 s, 1.2 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 8.48178 s, 1.2 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 8.99026 s, 1.1 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 8.80776 s, 1.2 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 10.2134 s, 1.0 MB/s
for i in $(seq 5); do dd if=/dev/zero of=/dev/sda2 bs=10K count=1000
oflag=direct; done
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 0.17393 s, 58.9 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 0.157572 s, 65.0 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 0.157324 s, 65.1 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 0.157506 s, 65.0 MB/s
1000+0 records in
1000+0 records out
10240000 bytes (10 MB) copied, 0.157329 s, 65.1 MB/s
---------------------------------------------------------------------------------
dump of drbd.conf:
global {
usage-count yes;
}
common {
protocol A;
syncer {
rate 400M;
}
}
resource r0 {
on mbus16 {
device /dev/drbd1;
disk /dev/sda2;
address 10.20.76.55:7789;
meta-disk internal;
}
on mbus16-backup {
device /dev/drbd1;
disk /dev/md2;
address 10.20.40.100:7789;
meta-disk internal;
}
}
----------------------------------------------------------------------------------------------------------------------------------------------------------------
Network latency is negligible:
# ping mbus16-backup.snc1
PING mbus16-backup.snc1 (10.20.40.100) 56(84) bytes of data.
64 bytes from mbus16-backup.snc1 (10.20.40.100): icmp_seq=1 ttl=62
time=0.158 ms
64 bytes from mbus16-backup.snc1 (10.20.40.100): icmp_seq=2 ttl=62
time=0.187 ms
64 bytes from mbus16-backup.snc1 (10.20.40.100): icmp_seq=3 ttl=62
time=0.186 ms
64 bytes from mbus16-backup.snc1 (10.20.40.100): icmp_seq=4 ttl=62
time=0.192 ms
64 bytes from mbus16-backup.snc1 (10.20.40.100): icmp_seq=5 ttl=62
time=0.152 ms
--
Lin Zhao
Data Platform Engineer
3101 Park Blvd, Palo Alto, CA 94306
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