From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Lange Subject: RE: Please review: Slackware RAID How-To Date: Wed, 19 May 2004 22:33:35 -0500 Sender: linux-raid-owner@vger.kernel.org Message-ID: <1085024014.6309.17.camel@ws101.darkcore.net> References: <200405170451.i4H4pqB05999@www.watkins-home.com> <1085017348.8670.26.camel@localhost> <1085018769.2042.32.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1085018769.2042.32.camel@localhost> To: office@ninti.com.au Cc: LinuxRaid List-Id: linux-raid.ids 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@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html