Re: xfs: very slow after mount, very slow at umount
From: david
Date: Fri Jan 28 2011 - 14:27:28 EST
On Sat, 29 Jan 2011, Dave Chinner wrote:
On Thu, Jan 27, 2011 at 06:09:58PM -0800, david@xxxxxxx wrote:
On Thu, 27 Jan 2011, Stan Hoeppner wrote:
david@xxxxxxx put forth on 1/27/2011 2:11 PM:
Picking the perfect mkfs.xfs parameters for a hardware RAID array can be
somewhat of a black art, mainly because no two vendor arrays act or perform
identically.
if mkfs.xfs can figure out how to do the 'right thing' for md raid
arrays, can there be a mode where it asks the users for the same
information that it gets from the kernel?
mkfs.xfs can get the information it needs directly from dm and md
devices. However, when hardware RAID luns present themselves to the
OS in an identical manner to single drives, how does mkfs tell the
difference between a 2TB hardware RAID lun made up of 30x73GB drives
and a single 2TB SATA drive? The person running mkfs should already
know this little detail....
that's my point, the person running mkfs knows this information, and can
easily answer questions that mkfs asks (or provide this information on the
command line). but mkfs doesn't ask for this infomation, instead it asks
the user to define a whole bunch of parameters that are not well
understood. An XFS guru can tell you how to configure these parameters
based on different hardware layouts, but as long as it remains a 'back
art' getting new people up to speed is really hard. If this can be reduced
down to
is this a hardware raid device
if yes
how many drives are there
what raid type is used (linear, raid 0, 1, 5, 6, 10)
and whatever questions are needed, it would _greatly_ improve the quality
of the settings that non-guru people end up using.
David Lang
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