Hi Dave, You can always break a backup job into multiple backup 'hosts' by using the ClientNameAlias setting. I create hosts based on the share or folder for each job, then use the ClientNameAlias to point them to the same host.
________________________________ From: Dave Sherohman <dave.sheroh...@ub.lu.se> Sent: Thursday, April 8, 2021 8:22 AM To: General list for user discussion, questions and support <backuppc-users@lists.sourceforge.net> Subject: [BackupPC-users] Handling machines too large to back themselves up I have a server which I'm not able to back up because, apparently, it's just too big. If you remember me asking about synology's weird rsync a couple weeks ago, it's that machine again. We finally solved the rsync issues by ditching the synology rync entirely and installing one built from standard rsync source code and using that instead. Using that, we were able to get one "full" backup, but it missed a bunch of files because we forgot to use sudo when we did it. (The synology rsync is set up to run suid root and is hardcoded to not allow root to run it, so we had to take sudo out for that, then forgot to add it back in when we switched to standard rsync.) Since then, every attempted backup has failed, either full or incremental, because the synology is running out of memory: This is the rsync child about to exec /usr/libexec/backuppc-rsync/rsync_bpc Xfer PIDs are now 1228998,1229014 xferPids 1228998,1229014 ERROR: out of memory in receive_sums [sender] rsync error: error allocating core memory buffers (code 22) at util2.c(118) [sender=3.2.0dev] Done: 0 errors, 0 filesExist, 0 sizeExist, 0 sizeExistComp, 0 filesTotal, 0 sizeTotal, 0 filesNew, 0 sizeNew, 0 sizeNewComp, 32863617 inode rsync_bpc: [generator] write error: Broken pipe (32) The poor little NAS has only 6G of RAM vs. 9.4 TB of files (configured as two sharenames, /volume1 (8.5T) and /volume2 (885G) and doesn't seem up to the task of updating that much at once via rsync. Adding insult to injury, even a failed attempt to back it up causes the bpc server to take 45 minutes to copy the directory structure from the previous backup before it even attempts to connect, and then 12-14 hours doing reference counts after it finishes backing up nothing. Which makes trial-and-error painfully slow, since we can only try one thing, at most, each day. In our last attempt, I tried flipping the order of the RsyncShareNames to do /volume2 first, thinking it might successfully back up the smaller share successfully before running out of memory trying to process the larger one. It did not run out of memory... but it did sit there for a full 24 hours with one CPU (out of four) running pegged at 99% handling the rsync process before we finally put it out of its misery. The bpc xferlog recorded that the connection was closed unexpectedly (which is fair, since we killed the other end) after 3182 bytes were received, so the client clearly hadn't started sending data yet. And now, after that attempt, the bpc server still lists the status as "refCnt #2" another 24 hours after the client-side rsync was killed. So, aside from adding RAM, is there anything else we can do to try to work around this? Would it be possible to break this one backup down into smaller chunks that are still recognized as a single host (so they run in sequence and don't get scheduled concurrently), but don't require the client to diff large amounts of data in one go, and maybe also speed up the reference counting a bit? An "optimization" (or at least an option) to completely skip the reference count updates after a backup fails with zero files received (and, therefore, no new/changed references to worry about) might also not be a bad idea.
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