On Mon, Jan 28, 2008 at 01:32:48PM -0500, Bill Davidsen wrote: > Neil Brown wrote: > >On Sunday January 27, keld@xxxxxxxx wrote: > > > >>Hi > >> > >>I have tried to make a striping raid out of my new 4 x 1 TB > >>SATA-2 disks. I tried raid10,f2 in several ways: > >> > >>1: md0 = raid10,f2 of sda1+sdb1, md1= raid10,f2 of sdc1+sdd1, md2 = raid0 > >>of md0+md1 > >> > >>2: md0 = raid0 of sda1+sdb1, md1= raid0 of sdc1+sdd1, md2 = raid01,f2 > >>of md0+md1 > >> > >>3: md0 = raid10,f2 of sda1+sdb1, md1= raid10,f2 of sdc1+sdd1, chunksize > >>of md0 =md1 =128 KB, md2 = raid0 of md0+md1 chunksize = 256 KB > >> > >>4: md0 = raid0 of sda1+sdb1, md1= raid0 of sdc1+sdd1, chunksize > >>of md0 = md1 = 128 KB, md2 = raid01,f2 of md0+md1 chunksize = 256 KB > >> > >>5: md0= raid10,f4 of sda1+sdb1+sdc1+sdd1 > >> > > > >Try > > 6: md0 = raid10,f2 of sda1+sdb1+sdc1+sdd1 > > > >Also try raid10,o2 with a largeish chunksize (256KB is probably big > >enough). > > > > Looking at the issues raised, there might be some benefit from having > the mirror chunks on the slower inner tracks of a raid10, and to read > from the outer tracks if the drives with the data on the outer tracks > are idle. This would appear to offer a transfer rate benefit overall. Hmm, how do I do this? I think this is normal behaviour of a raid10,f2. Is that so? So you mean I should rather use f2 than o2? Or should I configure the f2 in some way? My hdparm -t gives: /dev/sda5: Timing buffered beginning disk reads: 82 MB in 1.00 seconds = 81.686 MB/sec Timing buffered ending disk reads: 42 MB in 1.03 seconds = 40.625 MB/sec Average seek time 13.714 msec, min=4.641, max=23.921 Average track-to-track time 28.151 msec, min=26.729, max=28.730 So, yes, there is a reason to use the faster outer tracks - and have the faster access time that f2 gives . How does o2 behave here? Does it read and search on the whole disk? As to your other comments in another mail, I could of cause install a newer kernel and mdadm, but then I would loose the support of my supported and paid system. And Neil said that there have been no performance fixes for f2 since the kernel I use (2.6.12). I thought that o2 support was included since 2.6.10 - but apparantly not so. Best regards keld - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
