[DRBD-user] DRBD over 2 SSD and 40gbit infiniband

Matteo Tescione matteo at RMnet.it
Wed May 14 19:03:32 CEST 2014

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


drbd 8.4.4 running over a couple (software raid0/internal metadata) of SSD, local raid0 benchmark is 900MB/sec writing 1,2GB/sec reading, kernel is 3.12.14, interconnects with two Qlogic QLE7342 back-to-back in 40gbit infiniband QDR.

Iperf shows 1,2Gb/sec over tcp (mtu 65520) much more with rdma tests.

Resync rate is at 900M, but the initial resync was made at only 500Mb/sec. strange.

Formatting as ext4, both dd and bonnie++ show an avarage write speed of about 800Mb/sec, maybe 850-880 range. Which is quite good in drbd connected mode. 

Kernel is tuned in both tcp stacks and io stack, but I cannot understand why the resync rate is "ONLY" 500Mb/sec. Is the internal metadata updating cost that much even on an SSD subsystem?




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