Using stride on non-RAID
magawake at gmail.com
Mon May 9 22:40:20 UTC 2011
Are stride settings needed for Hardware RAID devices?
For example, if I do a RAID 5 on a HP-P800 I get a 9.1TB filesystem.
Should I worry about stride in that case?
On Wed, Mar 16, 2011 at 2:02 PM, David Shaw <dshaw at jabberwocky.com> wrote:
> On Mar 15, 2011, at 6:53 PM, Eric Sandeen wrote:
>> On 3/15/11 5:42 PM, David Shaw wrote:
>>> 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.
>> 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; 
>> Offhand I don't think it'd cause any harm to set stride on non-raid.
> Thanks very much for your pointers. It's a nice enhancement that this is done automatically now.
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