On Sunday 28 January 2007 22:21, you wrote: > On Sun, Jan 28, 2007 at 11:28:27AM -0800, Joe wrote: > > Some more tests: > > > > # dd if=/dev/zero of=./testfile count=1000000 > > 1000000+0 records in > > 1000000+0 records out > > 512000000 bytes transferred in 16.354 secs (31306797 bytes/sec) > > > > # dd if=./testfile of=/dev/null count=1000000 > > > > 1000000+0 records in > > 1000000+0 records out > > 512000000 bytes transferred in 6.013 secs (85137347 bytes/sec) > > > > So is 30MBps acceptable write speed for RAID 5 on a Compaq Smart Array > > 64xx controller? > > > > Could this be a driver issue? > > I doubt it: clearly it can transfer data at 85MBps, and it's unlikely that > the SCSI bus can transfer data faster in one direction than the other. > > I don't know this controller specifically, but maybe a better controller > would give you better RAID5 write performance. Or maybe something isn't > quite set up correctly on the card (e.g. if there's NVRAM write-through > cache, maybe the battery isn't present or it's disabled for some other > reason)
You're right. Most probably this guy joe is lacking Battery Backed Write Cache enabler. HP ships their boxes without it as default. This will likely give some performance penalty. I told him to check if he has a BBWC in a previous mail but as most idiots on misc he ignored it and sent another mail asking the same question. :-) Regards Johan M:son
