So I have been playing with a RAID 10 f2 ( 2 disks far layout) setup...thanks for all of the advice..Now I am playing with the format and want to make sure I have it setup the best that I can, my raid was built using the raid 10 option with 2 disks with the layout=far, chunk size 512....now I read all of the docs I could find about format and stride and stripe size and this is what i came up with... mkfs -t ext4 -E stride=128,stripe-width=32 /dev/md0 Someone let meknow if this looks right, but since i only have two disks to get my stride 512/4k=128 and then to get my stripe 2/2*128/4=32 Does that look right and if not let me know but more important how to obtain the right number so I can do it correctly in the future...Thanks. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos/attachments/20101001/4f5c4415/attachment-0002.html>
Tom Bishop wrote:> So I have been playing with a RAID 10 f2 ( 2 disks far layout) > setup...thanks for all of the advice..Now I am playing with the format > and want to make sure I have it setup the best that I can, my raid was > built using the raid 10 option with 2 disks with the layout=far, chunk > size 512....now I read all of the docs I could find about format and > stride and stripe size and this is what i came up with... > > mkfs -t ext4 -E stride=128,stripe-width=32 /dev/md0 > > > Someone let meknow if this looks right, but since i only have two > disks to get my stride 512/4k=128 and then to get my stripe 2/2*128/4=32I have this in my notes for ext2/ext3 filesystem under raid 5. You will have to see how your layout differs from raid5 in terms of distribution of data across the disks. # the optimal stride is given by: # # chunk size # stride = ---------- * ( num disks ) # block size # # Here is a framework of a script to test performance of various chunk sizes (came off of some webpage a while ago). Optimal chunk size will of course depend on your application and the size of your writes and files.. # # EXT2BLOCKSIZE=4096 # or 1024 or ??? # for CHUNKSIZE in 4 8 16 32 64 128 256 512 do stride=$(( $CHUNKSIZE * 1024 / $EXT2BLOCKSIZE )) .. .. create new /etc/raidtab and run the test .. mke2fs -b $EXT2BLOCKSIZE -m 1 -Rstride=$stride /dev/mdxx .. mount /dev/mdxx ..configurations # whatever test .. tiobench bonnie dd .. done # #
From: Tom Bishop <bishoptf at gmail.com>>So I have been playing with a RAID 10 f2 ( 2 disks far layout) setup...thanks >for all of the advice..Now I am playing with the format and want to make sure I>have it setup the best that I can, my raid was built using the raid 10 option >with 2 disks with the layout=far, chunk size 512....now I read all of the docs I > >could find about format and stride and stripe size and this is what i came up >with... >mkfs -t ext4 -E stride=128,stripe-width=32 /dev/md0 >Someone let meknow if this looks right, but since i only have two disks to get >my stride 512/4k=128 and then to get my stripe 2/2*128/4=32>From the mke4fs man page:"stripe-width ... This is typically stride-size * N, where N is the number of data-bearing disks in the RAID" So, I think it is 128 * 1 = 128 Also, have a look at: http://busybox.net/~aldot/mkfs_stride.html JD