On 21 April 2016 at 18:44, Chris Murphy <li...@colorremedies.com> wrote: > On Thu, Apr 21, 2016 at 6:53 AM, Martin Svec <martin.s...@zoner.cz> wrote: >> Hello, >> >> we use btrfs subvolumes for rsync-based backups. During backups btrfs often >> fails with "No space >> left" error and goes to readonly mode (dmesg output is below) while there's >> still plenty of >> unallocated space: > > Are you snapshotting near the time of enospc? If so it's a known > problem that's been around for a while. There are some suggestions in > the archives but I think the main thing is to back off on the workload > momentarily, take the snapshot, and then resume the workload. I don't > think it has to come to a complete stop but it's a lot more > reproducible with heavy writes.
Is this known problem specific to heavy writes + take a snapshot + -o compress (either zlib or lzo), or does this enospc also affect the more simple heavy writes + take a snapshot case? Is there a greater likelyhood of running into it if using compression? As for a workaround...is there a command like batch that can be used to schedule things for periods of low IO? Can a sync, btrfs fi sync /mountpoint, or btrfs sub sync /sub_mountpoint before taking a snapshot prevent it? If the answer to all of these is no, which of the following would be a good candidate for adding this support to: http://gnqs.sourceforge.net/docs/starter_pack/alternatives/index.html Best regards, Nicholas -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
