Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Am Dienstag, 2. Januar 2007 22:05 schrieb Ross S. W. Walker: > Hi there I am using DRBD 0.7.21 with iSCSI Enterprise Target 0.4.14 on > CentOS 4.4. > > When I run iSCSI direct to the LVM lv on top of hardware RAID I can get > 225 MB/s over two sessions in MPIO with 256K block size, but when I put > DRBD in-between iSCSI and LVM the throughput tops out at 80 MB/s and I > can't seem to go over that. > > DRBD seems to report it's max number of sectors as 8 (4K), does that > mean each io operation is limited to 4K? My hardware raid reports it's > max sectors as 128, could this explain the reduction to 1/3 throughput? > Hi, The cause for the limitation to 4k is the Linux-2.4 compabitility of DRBD-0.7. Repeat your test with drbd-8.0(rc1). drbd-8.0 will do BIOs up to 32k, but much more important are other changes (e.g. the non blocking make_request() function), that makes drbd-8.0 to scale much better with high end hardware. PS: What kind of network link are you using ? -Phil -- : Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Vivenotgasse 48, 1120 Vienna, Austria http://www.linbit.com :