More info! I found this comment in another group. It would indicate "stripe size" should be used. But it should not make a difference. Guy ======================================================================= The stride option places the inode and block bitmaps so that successive block groups' bitmaps are on a different RAID stripes. I suppose this might improve disk I/O performance, as the bitmaps are the most heavily used blocks on the disk. However, the cache should prevent most of the I/O in the first place... -----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of John Lange Sent: Wednesday, May 19, 2004 11:34 PM To: office@xxxxxxxxxxxx Cc: LinuxRaid Subject: RE: Please review: Slackware RAID How-To No, stride is not needed for RAID 1 as stride is about striping and RAID 1 does not do striping, it does mirroring. According to man raidtab, chunk-size "Sets the stripe size to size kilobytes.". So unless I'm completely off my rocker, chunk-size is also not needed for RAID 1 as it also only applies to striping. Thanks for pointing that out. I have removed it from my HowTo. I believe this error is also in the Software RAID HowTo which is where I copied my examples from. Regards, -- John Lange On Wed, 2004-05-19 at 21:06, Ninti Systems wrote: > But is the stride parameter required at all if I'm only building a RAID1 > array with two disks? > > Also, is the chunk size necessary in this case as I remember getting a > message on boot up to the effect that "Chunk size not necessary here, > but proceeding anyway!". > > Thanks > > Mick > > > On Thu, 2004-05-20 at 11:12, John Lange wrote: > > On Sun, 2004-05-16 at 23:51, Guy wrote: > > > md2 has 4 disks with a chunk size of 128K. Since only 3 disks are used for > > > data, and the filesystem block size is 4K, the stride size should be > > > 128*3/4, or 96. > > > Change: > > > mke2fs -b 4096 -R stride=32 /dev/md2 > > > To: > > > mke2fs -b 4096 -R stride=96 /dev/md2 > > > > > > My logic: > > > "Stripe size" is "chunk size" times "number of data disks". > > > From example: > > > "chunk size" = 128 > > > "number of data disks" = "nr-raid-disks" - 1 (-2 if RAID6) > > > > I think this is incorrect. At this point I defer to the > > Software-RAID-HOWTO. > > > > http://www.tldp.org/HOWTO/Software-RAID-HOWTO-5.html#ss5.10 > > > > >From that document stride is chucksize/blocksize . Number of disks does > > not enter into it. > > > > So with a chunksize of 128, and a block size of 4 it would be: > > > > 128K/4K = 32 for stride. > > > > If this is indeed correct I will be sure to expand that area of the > > How-To so it is more clear. > > > > Thanks very much for your feedback. > > > > Regards, > > > > John Lange > > > > - > > 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 - 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 - 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
