<br><font size=2 face="sans-serif">Hello, </font>
<br>
<br><font size=2 face="sans-serif"> I've
got strange problem with DRBD with Protocol C and fsync on files. Fsync
on primary machine costs about 2-4 seconds, and strange for me that this
is only on /var filesystems on server which has spools there, so I guess
its connected with changes on filesystem. </font>
<br>
<br><font size=2 face="sans-serif">Here is configuration for one of server:
</font>
<br>
<br><font size=2 face="sans-serif">global {</font>
<br><font size=2 face="sans-serif"> minor-count 6;</font>
<br><font size=2 face="sans-serif"> dialog-refresh 1;</font>
<br><font size=2 face="sans-serif">}</font>
<br><font size=2 face="sans-serif">resource var {</font>
<br><font size=2 face="sans-serif"> protocol C;</font>
<br><font size=2 face="sans-serif"> startup {</font>
<br><font size=2 face="sans-serif"> degr-wfc-timeout 120;
# 2 minutes.</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> disk {</font>
<br><font size=2 face="sans-serif"> on-io-error detach;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> net {</font>
<br><font size=2 face="sans-serif"> on-disconnect reconnect;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> syncer {</font>
<br><font size=2 face="sans-serif"> rate 680M;</font>
<br><font size=2 face="sans-serif"> group 1;</font>
<br><font size=2 face="sans-serif"> al-extents 257;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on primary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd0;</font>
<br><font size=2 face="sans-serif"> disk
/dev/ida/c0d0p5;</font>
<br><font size=2 face="sans-serif"> address 1.1.1.1:7788;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on secondary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd0;</font>
<br><font size=2 face="sans-serif"> disk /dev/cciss/c0d0p5;</font>
<br><font size=2 face="sans-serif"> address 1.1.2.2:7788;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif">}</font>
<br><font size=2 face="sans-serif">resource usr {</font>
<br><font size=2 face="sans-serif"> protocol C;</font>
<br><font size=2 face="sans-serif"> startup {</font>
<br><font size=2 face="sans-serif"> degr-wfc-timeout 120;
# 2 minutes.</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> disk {</font>
<br><font size=2 face="sans-serif"> on-io-error detach;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> net {</font>
<br><font size=2 face="sans-serif"> on-disconnect reconnect;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> syncer {</font>
<br><font size=2 face="sans-serif"> rate 680M;</font>
<br><font size=2 face="sans-serif"> group 1;</font>
<br><font size=2 face="sans-serif"> al-extents 257;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on primary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd1;</font>
<br><font size=2 face="sans-serif"> disk
/dev/ida/c0d0p6;</font>
<br><font size=2 face="sans-serif"> address 1.1.1.1:7789;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on secondary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd1;</font>
<br><font size=2 face="sans-serif"> disk /dev/cciss/c0d0p6;</font>
<br><font size=2 face="sans-serif"> address 1.1.2.2:7789;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif">}</font>
<br>
<br><font size=2 face="sans-serif">resource home {</font>
<br><font size=2 face="sans-serif"> protocol C;</font>
<br><font size=2 face="sans-serif"> startup {</font>
<br><font size=2 face="sans-serif"> degr-wfc-timeout 120;
# 2 minutes.</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> disk {</font>
<br><font size=2 face="sans-serif"> on-io-error detach;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> net {</font>
<br><font size=2 face="sans-serif"> on-disconnect reconnect;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> syncer {</font>
<br><font size=2 face="sans-serif"> rate 680M;</font>
<br><font size=2 face="sans-serif"> group 1;</font>
<br><font size=2 face="sans-serif"> al-extents 257;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on primary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd2;</font>
<br><font size=2 face="sans-serif"> disk
/dev/ida/c0d1p1;</font>
<br><font size=2 face="sans-serif"> address 1.1.1.1:7790;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif"> on secondary {</font>
<br><font size=2 face="sans-serif"> device /dev/drbd2;</font>
<br><font size=2 face="sans-serif"> disk /dev/cciss/c0d0p7;</font>
<br><font size=2 face="sans-serif"> address 1.1.1.2.2:7790;</font>
<br><font size=2 face="sans-serif"> meta-disk internal;</font>
<br><font size=2 face="sans-serif"> }</font>
<br><font size=2 face="sans-serif">}</font>
<br>
<br><font size=2 face="sans-serif">Current /proc/drbd on primary machine:
</font>
<br><font size=2 face="sans-serif">version: 0.7.10 (api:77/proto:74)</font>
<br><font size=2 face="sans-serif">SVN Revision: 1743 build by root@debian,
2004-11-11 15:10:16</font>
<br><font size=2 face="sans-serif"> 0: cs:Connected st:Primary/Secondary
ld:Consistent</font>
<br><font size=2 face="sans-serif"> ns:153776 nr:0 dw:1009555868
dr:85196925 al:1947 bm:1520 lo:0 pe:0 ua:0 ap:0</font>
<br><font size=2 face="sans-serif"> 1: cs:Connected st:Primary/Secondary
ld:Consistent</font>
<br><font size=2 face="sans-serif"> ns:419888 nr:0 dw:33664956
dr:16916101 al:15 bm:431 lo:0 pe:0 ua:0 ap:0</font>
<br><font size=2 face="sans-serif"> 2: cs:Connected st:Primary/Secondary
ld:Consistent</font>
<br><font size=2 face="sans-serif"> ns:5757168 nr:0 dw:638144400
dr:626179845 al:308612 bm:2781 lo:0 pe:0 ua:0 ap:0</font>
<br>
<br><font size=2 face="sans-serif">The only thing which connects all these
servers is high DW count. I know its high becouse of many changes on that
filesystem. AP never goes big. Filesystem is not highly used when I do
fsync on written file. Fsyncing on other DRBD mount points on that server
works fast as it should. </font>
<br>
<br><font size=2 face="sans-serif">As it is production enviroment I could
only rebuild drbd disk on secondary server. But if this will be needed
for debuging process I can switch off primary on off hours. </font>
<br><font size=2 face="sans-serif">For fast workaround I did set Protocol
B on that var mount point, but I'm not satisfied with this. Could anyone
explain why that happends and how to avoid this? </font>
<br>
<br><font size=2 face="sans-serif">Best regards,</font>
<br><font size=2 face="sans-serif"><br>
-- <br>
Sylwester Żelazko<br>
PolCard S.A. (Zespół Administracji Systemami)<br>
(22)-515-38-04</font>