Note that stride and stripe width only make sense for RAI-5/6 arrays. For RAID-1 it doesn't really matter. Cheers, Andreas > On Mar 6, 2014, at 13:46, Martin T <m4rtntns@xxxxxxxxx> wrote: > > Hi, > > I created a RAID1 array of two physical HDD's with chunk size of 64KiB under Debian "wheezy" using mdadm. As a next step, I would like to create an ext3(or ext4) file-system to this RAID1 array using mke2fs utility. According to RAID-related tutorials, I should create the file-system like this: > > # mkfs.ext3 -v -L myarray -m 0.5 -b 4096 -E stride=16,stripe-width=32 /dev/md0 > > > Questions: > > 1) According to manual of mke2fs, value of the "stride" has to be the RAID chunk size in clusters. As I use chunk size of 64KiB, then I have to use "stride" value of 16(16*4096=65536). Why is it important for file-system to know the size of chunk used in RAID array? I know it improves the I/O performance, but why is this so? > > 2) If the "stride" size in my case is 16, then the "stripe_width=" is 32 because there are two drives in the array which contain the actual data. Manual page of the mke2fs explain this option as "This allows the block allocator to prevent read-modify-write of the parity in a RAID stripe if possible when the data is written.". How to understand this? What is this "read-modify-write" behavior? Could somebody explain this with an example? > > > regards, > Martin > _______________________________________________ > Ext3-users mailing list > Ext3-users@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/ext3-users _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
