[DRBD-user] Initial Sync - Fast then really slow

Travis Kriza travman at mtcperformance.com
Fri Apr 9 01:27:32 CEST 2004

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

> please reproduce it without heartbeat...  "by hand"
> Thanks.


	I actually experienced that fast then slow condition actually without 
heartbeat.  (I was wondering what had been happening originally and was 
manually starting the drbd processes on each box).  Anyways, after 
setting up NTP and resyncing the clocks (and a reboot), I was able to 
achieve pretty good throughput speeds.

However, now I'm noticing I may have too much of a bottleneck between 
running a software RAID 1 on each box PLUS the drbd raid of those raid 
1 volumes.  I'm running some iozone tests first to see if I get 
noticeable improvements in performance.  (Basically, I had apache 
logging via NFS to this pair of boxes, and the box ended up scaling out 
of control with load --- that is, the apache box went up to like a load 
of 20 whereas the nfs box went up to maybe a 2).  Anyways, I was 
thinking to improve performance, it may make sense to switch the shared 
(drbd shared) drives to be based on a raid0 volume versus the raid 1.  
(I was also thinking it may be wiser to either pipe the apache logs to 
write to both spots, or simply do a regular rsync interval for the 
logs).  Any thoughts on this?

And, can anyone recommend an easy way to convert a raid 1 into a raid 
0?  doing partition management during install is easy with disk druid, 
but i'm lousy at disk management when it comes command line.  Never had 
to deal with it that much.



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