[DRBD-user] Slow sync speeds

Brandon Laing Brandon.Laing at vancoservices.com
Thu Mar 4 18:51:02 CET 2004

Hey all,

Thanks to the advice I received yesterday, DRBD is now up and running and syncing data between 2 systems. However, it seems to be going extremely slow. As a test, I copied about 14MB of data onto the primary system to sync it up. What I'm seeing is that it takes about 3 and a half hours to sync that much data. Data which I copied off of the network in about 5 seconds. I'm not expecting this to be as fast as that, but I wouldn't expect it to take well over 3 hours either. So here's what I've done so far:

Modified the sync-min and sync-max files in the drbd.conf file, as well as changed them through the drbdsetup command. Currently set as sync-min = 20M and sync-max = 100M. Current speeds shown by cat /proc/drbd: 11,252 K/sec. Changing these values did not impact the speed at all.

So, I changed the sync-nice value, which was set at -18 initially. Tried -10, 1, and 20... again, no difference in speeds or usage. 

Both systems are identical, running the following hardware on Fedora 1 on the 2.4.22-1.2115 kernel:

P4 2 GHz
Hardware RAID-5 array on 3ware 7506 controllers (3 80GB Maxtor disks with 8MB buffers)
Intel Pro 100/1000 MT server adapters with the latest drivers (both with a full duplex connection)

These 2 systems are only 2 switches apart on the network, so I'm thinking that I should be seeing a little bit better speeds. Or, does this sound about right? Any advice would be appreciated, and if any additional config info is needed, just ask.


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