swin wang wrote:
We have tested the 1.5.97, and set qos_priofree, but it didn't work,
I think qos_priofree just make different penalty to OST, it can not avoid
alloc object on the full OST.
Are you sure qos_priofree can do it?
You are correct; it just changes the penalty. QOS does not ever
guarantee that any particular OST will or won't be used - it only
changes the likelihood.
You can prevent the MDT from assigning new stripes to a particular OST
by deactivating the corresponding OSC on the MDT using "lctl
deactivate", but this has to be done every time the MDT is restarted.
You could also use
mount -o exclude=testfs-OST0000 -t lustre /dev/mdt /mnt/mdt
at MDT mount time for the same result.
You could also change the line in filter_precreate()
if (rc == 0 && osfs->os_bavail < (osfs->os_blocks >> 10))
blocks >> 10 = blocks / 1024 = 0.1%,
you could just change it to os_blocks / 10 for an automatic 10% free
space limit.
2007/4/18, Andreas Dilger <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>:
On Apr 18, 2007 16:19 +0800, swin wang wrote:
> We hope that if an OST's used rate up to 90% or 95%, it can
be marked
> FULL, and avoid to use this OST. we plan to add a state FULL in
structure
> lov_tgt_desc, when the
> OST used rate up to 90% or 95%, set its state to FULL, and
when create
> new object,
> don't use these FULL OST.
> We want to know how to calculate used rate of a OST, is it
like this:
> used rate =
lov->lov_tgts[i]->ltd_exp->exp_obd->obd_osfs.os_bavail /
> ov->lov_tgts[i]->ltd_exp->exp_obd->obd_osfs.os_blocks ??
This is already done on the OSTs in filter_precreate(), though the
limit is
only 0.1%. I'd be happy to accept a patch which made this limit a
tunable
in /proc that can be set by the sysadmin.
There is also in 1.6 (and betas) some free space management that
is tunable
on the MDS /proc/fs/lustre/lov/*/qos_priofree which is a
percentage of
weight which you want to give to "free" OSTs. In your case you
want this
to be relatively high (90% is the default in later betas). If
this is not
sufficient to have the MDS allocate very preferentially on free
OSTs, please
provide more details on your configuration.
Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.
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