Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi, Why people keep using bad hardware after million posts on the ML reporting bad results? Please, before using some RAID card, do a quick search on the mailing lists and learn with other mistakes instead of doing the same mistakes. :-) 3ware cards are bad piece of crap. Use other cards, like Areca. Cheers, On 31-08-2011 12:46, Florian Apolloner wrote: > Hi, > > I am having a horrible latency with the following configuration: > > * protocol c > * raid5 over a 3Ware 9750-4i SAS2 raid controller > * Dedicated Gigabit link between the two machines, no switch in between. > > This is what I can tell you: > > * iperf shows around 950 Mbits/sec -- sounds okay for gigabit ;) > * throughput for the drbd raid has 70-80 MByte/sec -- sounds good to me > too. > > Now on to the latency tests (backing device): > > dd if=/dev/zero of=/dev/sda3 bs=512 count=1000 oflag=direct > 512000 bytes (512 kB) copied, 0.0365779 seconds, 14.0 MB/s > > and onto the drbd device: > > dd if=/dev/zero of=/dev/drbd1 bs=512 count=1000 oflag=direct > 512000 bytes (512 kB) copied, 9.651 seconds, 53.1 kB/s > > Sounded awfully slow to me, so I compared with a ramdisk: > > dd if=/dev/zero of=/dev/drbd2 bs=512 count=1000 oflag=direct > 512000 bytes (512 kB) copied, 0.166689 seconds, 3.1 MB/s > > Sounds waaaay better, though I can't tell if that's slow or fast enough. > > The RTT for the link is: > rtt min/avg/max/mdev = 0.096/0.166/0.207/0.043 ms > > So let's summarize: > > -> Harddisk speed shouldn't be a problem (0.0365779 seconds for the write) > -> Network speed should be a problem as indicated by RTT and iperf > > -> Network and Harddisk combined -> problems. > > Any hints on how to debug that? I am currently grasping any straw I can > get :/ > > Thx in advance and regards, > Florian Apolloner > > > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user -- Igor Neves<igor.neves at 3gnt.net> 3GNTW - Tecnologias de Informação, Lda SIP: igor at 3gnt.net MSN: igor at 3gnt.net JID: igor at 3gnt.net PSTN: 00351 252377120 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20110901/dc74327f/attachment.htm>