Robin Humble wrote:
On Thu, Jan 17, 2008 at 01:34:46PM +0300, Vladislav Bolkhovitin wrote:
Hmm, I can't find which IB hardware did he use and it's declared Gbps
speed. He declared only "Mellanox 4X SDR, switch". What does it mean?
SDR is 10Gbit carrier, at most about ~900MB/s data rate.
DDR is 20Gbit carrier, at most about ~1400MB/s data rate.
Thanks. Then the single threaded rate with one outstanding command
between SCST SRP on 8Gbps link vs STGT iSRP on 10Gbps link (according to
that paper) is 600MB/s vs ~480MB/s (page 26). Still SCST based target is
about 60% faster.
On Thu, 17 Jan 2008 10:27:08 +0100 "Bart Van Assche" <bart.vanassche@xxxxxxxxx> wrote:
Test performed: read 2 GB of data in blocks of 1 MB from a target (hot
cache -- no disk reads were performed, all reads were from the cache).
Test command: time dd if=/dev/sde of=/dev/null bs=1M count=2000
STGT read SCST read
performance (MB/s) performance (MB/s)
Ethernet (1 Gb/s network) 77 89
IPoIB (8 Gb/s network) 82 229
SRP (8 Gb/s network) N/A 600
iSER (8 Gb/s network) 80 N/A
it kinda looks to me like the tgt iSER tests were waaay too slow to be
using RDMA :-/
I use tgt to get 500MB/s writes over iSER DDR IB to real files (not
ramdisk). Reads are a little slower, but that changes a bit with distro
vs. mainline kernels.
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