Most are moderate to highly compressible files which is why I'm trying so hard to figure this one out. On average I seem to hit about 50% and the file sizes for what I care about compressing are from 10M up to around 1G. I'm looking at saving around 700T of space on this tier. Loving the ideas. I know one of these is going to be the "Why the hell didn't I think of that" statements. I think while the OSD drain/refill is cooking in the background I will stand up a second pool on the same disks to do some testing with. Copy a few T of data in with compression off, see what the numbers look like, try to dance it around, blow it away and do it again with compression on. -- Paul Mezzanini Sr Systems Administrator / Engineer, Research Computing Information & Technology Services Finance & Administration Rochester Institute of Technology o:(585) 475-3245 | pfmeec@xxxxxxx CONFIDENTIALITY NOTE: The information transmitted, including attachments, is intended only for the person(s) or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and destroy any copies of this information. ------------------------ ________________________________ From: Thorbjørn Weidemann <thorbjoern@xxxxxxxxxxxxxx> Sent: Monday, January 4, 2021 4:39 PM To: Paul Mezzanini Cc: DHilsbos@xxxxxxxxxxxxxx; ceph-users@xxxxxxx Subject: Re: Re: Compression of data in existing cephfs EC pool CAUTION: This message came from outside RIT. If you are unsure about the source or content of this message, please contact the RIT Service Center at 585-475-5000 or help.rit.edu before clicking links, opening attachments or responding. I have not tried this myself, but could it be related to the compress_required_ratio mentioned here? https://books.google.dk/books?id=vuiLDwAAQBAJ&pg=PA80&lpg=PA80 zip-files probably can't be compressed all that much. On Mon, Jan 4, 2021 at 9:44 PM Paul Mezzanini <pfmeec@xxxxxxx<mailto:pfmeec@xxxxxxx>> wrote: I'm using rsync so I can have it copy times/permissions/acl's etc easier. It also has an output that's one line per file and informative. Actual copy line: rsync --owner --group --links --hard-links --perms --times --acls --itemize-changes "${DIRNAME}/${FILENAME}" "${DIRNAME}/.${FILENAME}.copying" It makes a new file unless it is a link to another file (which it shouldn't be because the find command I used to generate the list excluded them) [pfmeec@gung testing]$ ls -il SMT_X11AST2500_164.zip ; sudo ../wiggler.sh /home/pfmeec/testing/SMT_X11AST2500_164.zip ; ls -il SMT_X11AST2500_164.zip 1101787638344 -rw-r--r--. 1 pfmeec staff 27831340 Jan 4 15:34 SMT_X11AST2500_164.zip >f+++++++++ SMT_X11AST2500_164.zip 1101787638345 -rw-r--r--. 1 pfmeec staff 27831340 Jan 4 15:34 SMT_X11AST2500_164.zip [pfmeec@gung testing]$ It does have a new inode number, but it feels suspect that the number is only one digit higher. Probably largely because I did several runs in a row to verify and it was just the next inode handed out. -- Paul Mezzanini Sr Systems Administrator / Engineer, Research Computing Information & Technology Services Finance & Administration Rochester Institute of Technology o:(585) 475-3245 | pfmeec@xxxxxxx<mailto:pfmeec@xxxxxxx> CONFIDENTIALITY NOTE: The information transmitted, including attachments, is intended only for the person(s) or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and destroy any copies of this information. ------------------------ ________________________________________ From: DHilsbos@xxxxxxxxxxxxxx<mailto:DHilsbos@xxxxxxxxxxxxxx> <DHilsbos@xxxxxxxxxxxxxx<mailto:DHilsbos@xxxxxxxxxxxxxx>> Sent: Monday, January 4, 2021 3:27 PM To: Paul Mezzanini; ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> Subject: RE: Re: Compression of data in existing cephfs EC pool Paul; I'm not familiar with rsync, but is it possible you're running into a system issue of the copies being shallow? In other words, is it possible that you're ending up with a hard-link (2 directory entries pointing to the same initial inode), instead of a deep copy? I believe CephFS is implemented such that directories and their entries are omaps, while inodes are data objects. If your operating system / filesystem / copy mechanism isn't creating new inodes, and deleting the old ones, they wouldn't get compressed. Confirmation from a Ceph dev on the above implementation assumptions would be appreciated. Thank you, Dominic L. Hilsbos, MBA Director - Information Technology Perform Air International Inc. DHilsbos@xxxxxxxxxxxxxx www.PerformAir.com<http://www.PerformAir.com> -----Original Message----- From: Paul Mezzanini [mailto:pfmeec@xxxxxxx<mailto:pfmeec@xxxxxxx>] Sent: Monday, January 4, 2021 11:23 AM To: Burkhard Linke; ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> Subject: Re: Compression of data in existing cephfs EC pool That does make sense and I wish it were true however what I'm seeing doesn't support your hypothesis. I've had several drives die and be replaced since the go-live date and I'm actually in the home stretch on reducing the pg_num on that pool so pretty much every PG has already been moved several times over. It's also possible that my method for checking compression is flawed. Spot checks from what I can see in an OSD stat dump and ceph df detail seem to line up so I don't believe this is the case. The only time I see the counters move is when someone puts new data in via globus or migration from a cluster job. I will test what you proposed though by draining an OSD and refilling it then checking the stat dump to see what lives under compression and what does not. -paul -- Paul Mezzanini Sr Systems Administrator / Engineer, Research Computing Information & Technology Services Finance & Administration Rochester Institute of Technology o:(585) 475-3245 | pfmeec@xxxxxxx<mailto:pfmeec@xxxxxxx> CONFIDENTIALITY NOTE: The information transmitted, including attachments, is intended only for the person(s) or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and destroy any copies of this information. ------------------------ ________________________________________ Just my two cents: Compression is an OSD level operation, and the OSD involved in a PG do no know about each others' compression settings. And they probably also do not care, considering the OSD to be a black box. I would propose to drain OSDs (one by one or host by host by setting osd weights) to move the uncompressed data off. Reset the weights to the former values later to move the data back, and upon writing the data it should be compressed. Compression should also happen during writing the data to other osds when it is moved an OSD, but you will end up with a mix of compressed and uncompressed data on the same OSD. You will have to process all OSDs). If this is working as expected, you do not have to touch the data on the filesystem level at all. The operation happens solely on the underlying storage. Regards, Burkhard _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> To unsubscribe send an email to ceph-users-leave@xxxxxxx<mailto:ceph-users-leave@xxxxxxx> _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> To unsubscribe send an email to ceph-users-leave@xxxxxxx<mailto:ceph-users-leave@xxxxxxx> _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> To unsubscribe send an email to ceph-users-leave@xxxxxxx<mailto:ceph-users-leave@xxxxxxx> _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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