[DRBD-user] DRBD slow sync

Tomasz Chmielewski mangoo at wpkg.org
Mon May 19 16:19:09 CEST 2008

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


Anže Vidmar schrieb:
> hello list!
> 
> I've setup a fresh install of DRBD + OCFS2 on the machine with the 
> following properties:
> 
> OS: (Bluewhite64 12) Linux 2.6.23.9-2
> ARCH: x86_64
> CPU:8 x Intel(R) Xeon(R) CPU E5430  @ 2.66GHz
> eth0 = 1Gb
> DRBD version =  8.2.5
> 
> The problem is that DRBD sync in very slooooow, around 315k/s. There is 
> no way I can speed-up the process. The storage with OCFS2 is 3.2T large 
> and it's build on hardware RAID5 + 1 spare.
> 
> Here is what I've already did:
> 
> - changed the UTP cable (cross and regular)
> - tried with kernel that has DRBD included in, and kernel + DRBD module
> - I've test the data transfer directly on eth1 - the transfer was normal 
> aroung 75M/s, so the link between the secondary (eth1) NIC's is ok
> - played with ethtool - I've setup the card to 100/1000M, half/full 
> duplex... No change
> - tweaking drbd.conf "net" parameters. No speed change at all.
> 
> Anyone have any idea what might be causing the slow sync? Is this normal 
> for the 1st time sync?

According to http://www.drbd.org/users-guide/re-drbdconf.html the 
default rate is just 250 KB/s:

rate rate

     To ensure a smooth operation of the application on top of DRBD, it 
is possible to limit the bandwidth which may be used by background 
synchronizations. The default is 250 KB/sec, the default unit is KB/sec. 
Optional suffixes K, M, G are allowed.


-- 
Tomasz Chmielewski
http://wpkg.org





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