Poor write performance when replication is on

[juelz]

Hello,

I've set up a replication between two DSS servers.

When I start the replication process, it synchronizes both volumes and reports "Consistent" on each volume. I start copying files then (or dd'ing some data) to the iSCSI volume, but this is really slow (dd reports 5-10 mb/s). When I turn off the replication, the write throughput is from 80 to 100 mb/s (which i quite good for a 1 gbit/s network).

Both servers are linked directly to each other using a cat 6 patchcable (crossover is not needed, because both NIC's support Auto-MDI-X). drbd initially synchronizes the volumes also with 80 to 100 mb/s speed.

What could be the bottleneck, when replication is turned on?

Thanks!

[To-L]

Please set a higher value for the parameter VMALLOC. This
can be done via the console tools (CTRL+ALT+W > Tuning Options > Vmalloc
size).
Are you connecting to the destination directly, and you are connecting to the source from another NIC.

[juelz]

Hi,

I increased vmalloc to 384mb on both servers, but the problems still exists.

2097152000 bytes (2.1 GB) copied, 473.446 s, 4.4 MB/s

Both servers are connected directly through crossover cable (eth3 on both, 1 gbit/s). The iSCSI initiators are accessing the source through eth4 & 5 (bonded, 2 gbit/s).

Any ideas?

[To-M]

What is the version of DSS you are running?

[juelz]

Version:                        5.0.DB47000000.3216
Release date:                   2008-08-28

[To-L]

Please upgrade to the latest version of DSS
Here is the link:
http://www.open-e.com/account/products-and-updates/