Re: Using stride on non-RAID

On 3/15/11 5:42 PM, David Shaw wrote:
> Hello,
> 
> I understand the need for a proper stride setting when formatting a
> filesystem on a RAID device.  However, is there any problem in using
> a stride setting when formatting a filesystem on a regular non-RAID,
> non-SSD, just plain-vanilla-single-disk block device?  I'm sure there
> isn't any benefit to it, but I'm curious if there is any harm.
> 
> The reason I ask is I'm looking at some code here that can be used on
> either RAID or non-RAID devices.  The stride setting it has is
> correct for the particular RAID setup it is intended for, but it also
> uses those settings when formatting a non-RAID device.
> 
> David

just FWIW, recent kernels & e2fsprogs will just automatically pick
stride based on storage geometry - for md/lvm at least, and for
scsi devices that export this geometry as well.

ext4 has a little stripe-awareness in its allocator; otherwise, stride
just staggers bitmap starts so they don't all end up on the same spindle; [1]
Offhand I don't think it'd cause any harm to set stride on non-raid.

-Eric

[1] ext2fs_allocate_group_table() in lib/ext2fs/alloc_tables.c