[DRBD-user] slow sync speed of 12TB over 10GE

Jürgen Scholz juergen at kernkraft400.com
Mon Jan 12 14:15:03 CET 2009


Hello!

> I'm new to the topic but managed to get a mirrored setup working.
> The only problem is the sync speed:
After all what Igor has said there is one thing that popped into my  
mind:
Maybe you want to put the metadata onto a non-RAID5-disk.
I remember that Lars mentioned a serious performance degradation if  
the metadata is on a RAID5, because the metadata changes often. With  
hardware RAID this is not as serious qs with software RAID, because  
normally there is a big (and battery backed!!) cache on them.
The performance degradation seen in synchronisation due to the "slow"  
metadata blockdevice will also strike in regular use. You may want to  
do something about it.

Please correct me if i'm wrong here!

What i would do:
Use two disks in a RAID1 configuration for the OS and metadata. You  
should be fine then. The only problem is: you'll lose available  
harddisk space.

hth,
  juergen



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