Perhaps IBM might consider letting you commit it to
https://github.com/gpfsug/gpfsug-tools he says, asking out loud... It'll
require a friendly IBMer to take the reins up for you. Scott? :-)
Jez
On 03/08/17 02:00, Aaron Knister wrote:
I'm a little late to the party here but I thought I'd share our recent
experiences.
We recently completed a mass UID number migration (half a billion
inodes) and developed two tools ("luke filewalker" and the
"mmilleniumfacl") to get the job done. Both luke filewalker and the
mmilleniumfacl are based heavily on the code in
/usr/lpp/mmfs/samples/util/tsreaddir.c and
/usr/lpp/mmfs/samples/util/tsinode.c.
luke filewalker targets traditional POSIX permissions whereas
mmilleniumfacl targets posix ACLs. Both tools traverse the filesystem
in parallel and both but particularly the 2nd, are extremely I/O
intensive on your metadata disks.
The gist of luke filewalker is to scan the inode structures using the
gpfs APIs and populate a mapping of inode number to gid and uid
number. It then walks the filesystem in parallel using the APIs, looks
up the inode number in an in-memory hash, and if appropriate changes
ownership using the chown() API.
The mmilleniumfacl doesn't have the luxury of scanning for POSIX ACLs
using the GPFS inode API so it walks the filesystem and reads the ACL
of any and every file, updating the ACL entries as appropriate.
I'm going to see if I can share the source code for both tools,
although I don't know if I can post it here since it modified existing
IBM source code. Could someone from IBM chime in here? If I were to
send the code to IBM could they publish it perhaps on the wiki?
-Aaron
On 6/30/17 11:20 AM, [email protected] wrote:
Hello,
We're trying to change most of our users uids, is there a clean
way to
migrate all of one users files with say `mmapplypolicy`? We have to
change the
owner of around 273539588 files, and my estimates for runtime are
around 6 days.
What we've been doing is indexing all of the files and splitting
them up by
owner which takes around an hour, and then we were locking the user
out while we
chown their files. I made it multi threaded as it weirdly gave a 10%
speedup
despite my expectation that multi threading access from a single node
would not
give any speedup.
Generally I'm looking for advice on how to make the chowning
faster. Would
spreading the chowning processes over multiple nodes improve
performance? Should
I not stat the files before running lchown on them, since lchown
checks the file
before changing it? I saw mention of inodescan(), in an old gpfsug
email, which
speeds up disk read access, by not guaranteeing that the data is up
to date. We
have a maintenance day coming up where all users will be locked out,
so the file
handles(?) from GPFS's perspective will not be able to go stale. Is
there a
function with similar constraints to inodescan that I can use to
speed up this
process?
Thank you for your time,
Luke
Storrs-HPC
University of Connecticut
_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at spectrumscale.org
http://gpfsug.org/mailman/listinfo/gpfsug-discuss
--
*Jez Tucker*
Head of Research and Development, Pixit Media
07764193820 | [email protected] <mailto:[email protected]>
www.pixitmedia.com <http://www.pixitmedia.com> | Tw:@pixitmedia.com
<https://twitter.com/PixitMedia>
--
<http://pixitmedia.com>
This email is confidential in that it is intended for the exclusive
attention of the addressee(s) indicated. If you are not the intended
recipient, this email should not be read or disclosed to any other person.
Please notify the sender immediately and delete this email from your
computer system. Any opinions expressed are not necessarily those of the
company from which this email was sent and, whilst to the best of our
knowledge no viruses or defects exist, no responsibility can be accepted
for any loss or damage arising from its receipt or subsequent use of this
email.
_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at spectrumscale.org
http://gpfsug.org/mailman/listinfo/gpfsug-discuss
