[DRBD-user] Dual-primary/ Very slow synchronization

Daniel Meszaros spam at meszi.de
Fri May 20 10:12:29 CEST 2011

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


Hi!

Am 19.05.2011 21:16, schrieb Digimer:
> As Felix stated, try 10M. If it get's up to that speed (and it can take
> a while, be patient), then bump it to 20M, etc.

I tried syncing with 10M last night and indeed it became faster than 
before and was around 10MB/s. Using "drbdsetup /dev/drbd0 syncer -r 20M" 
and so on I could increase the sync speed up to 70M ... then it 
interrupted and a new bitmap check started.

While doing so I recognized some kernel error message in my virtual 
guests of the Xenserver:

Linux:
[ 2040.064272] INFO: task exim4:2336 blocked for more than 120 seconds.
[ 2040.064281] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.

Windows 2003 SBS:
NTDS (432) NTDSA: Eine Anforderung, von der Datei 
"C:\WINDOWS\NTDS\ntds.dit" ab Offset 4661248 (0x0000000000472000) 
insgesamt 8192 (0x00002000) Bytes zu lesen, war erfolgreich, benötigte 
aber ungewöhnlich viel Zeit (406 Sekunden) von Seiten des 
Betriebssystems. Zusätzlich haben 0 andere E/A-Anforderungen an diese 
Datei ungewöhnlich viel Zeit benötigt, seit die letzte Meldung bezüglich 
dieses Problems vor 539 Sekunden gesendet wurde. Dieses Problem ist 
vermutlich durch fehlerhafte Hardware bedingt. Wenden Sie sich für 
weitere Unterstützung bei der Diagnose des Problems an Ihren 
Hardwarehersteller.

While this is happening these machines are not available in the network. 
Therefore I stopped the synchronization and shut down the machine that 
is out of sync ... which led back to normally working services.

For any reason the DRBD sync appears to take too much I/O performance, 
even if it is running at 10M. I must admit that the last time I remember 
having done a full sync was before I had these machines set up and running.

When asking Google I found emails from this list I found some message 
mentioning "scst vdisk_blockio" to be changed to "vdisk_fileio", however 
I do not use SCST.

Any ideas on non-SCST systems? :-/

CU,
Mészi.




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