Re: Read I/O starvation with writeback RAID controller

2013-02-22 Thread Martin Svec
Hi, Dne 21.2.2013 23:01, Nicholas A. Bellinger napsal(a): Hi Martin, On Thu, 2013-02-21 at 12:43 +0100, Martin Svec wrote: > I'm sorry, I forgot to mention hardware details. It isn't aacraid, it > is megaraid-based Dell PERC H700 w/ 1GB NVRAM and 12x 450GB 15k SAS > dri

Re: Read I/O starvation with writeback RAID controller

2013-02-21 Thread Martin Svec
;ing linux-scsi here, as aacraid doesn't have an official maintainer > atm. > > --nab > > On Wed, 2013-02-20 at 16:38 +0100, Martin Svec wrote: >> Hello, >> >> I've noticed read I/O starvation problems of LIO iSCSI target when >> used on top o

Read I/O starvation with writeback RAID controller

2013-02-20 Thread Martin Svec
Hello, I've noticed read I/O starvation problems of LIO iSCSI target when used on top of writeback-enabled HW RAID controller (PERC H700 with 1GB cache). For intensive mixed read-write workload in virtualized environments, writes are able to consume over 95% of the IOPS throughput and cause starva