The most useful thing that folks can provide is an indication of what was writing to those data files when you were doing backups.
It's almost certainly one of: - Memtable flush - Compaction - Streaming from repair/move/bootstrap If you have logs that indicate compaction starting/finishing with those sstables, or memtable flushing those sstables, or if the .log file is included in your backup, pasting the contents of that .log file into a ticket will make this much easier to debug. On Tue, Mar 22, 2022 at 9:49 AM Yifan Cai <yc25c...@gmail.com> wrote: > I do not think there is a ticket already. Feel free to create one. > https://issues.apache.org/jira/projects/CASSANDRA/issues/ > > It would be helpful to provide > 1. The version of the cassandra > 2. The options used for snapshotting > > - Yifan > > On Tue, Mar 22, 2022 at 9:41 AM Paul Chandler <p...@redshots.com> wrote: > >> Hi all, >> >> Was there any further progress made on this? Did a Jira get created? >> >> I have been debugging our backup scripts and seem to have found the same >> problem. >> >> As far as I can work out so far, it seems that this happens when a new >> snapshot is created and the old snapshot is being tarred. >> >> I get a similar message: >> >> /bin/tar: >> var/lib/cassandra/backup/keyspacename/tablename-4eec3b01aba811e896342351775ccc66/snapshots/csbackup_2022-03-22T14\\:04\\:05/nb-523601-big-Data.db: >> file changed as we read it >> >> Thanks >> >> Paul >> >> >> >> On 19 Mar 2022, at 02:41, Dinesh Joshi <djo...@apache.org> wrote: >> >> Do you have a repro that you can share with us? If so, please file a jira >> and we'll take a look. >> >> On Mar 18, 2022, at 12:15 PM, James Brown <jbr...@easypost.com> wrote: >> >> This in 4.0.3 after running nodetool snapshot that we're seeing sstables >> change, yes. >> >> James Brown >> Infrastructure Architect @ easypost.com >> >> >> On 2022-03-18 at 12:06:00, Jeff Jirsa <jji...@gmail.com> wrote: >> >>> This is nodetool snapshot yes? 3.11 or 4.0? >>> >>> In versions prior to 3.0, sstables would be written with -tmp- in the >>> name, then renamed when complete, so an sstable definitely never changed >>> once it had the final file name. With the new transaction log mechanism, we >>> use one name and a transaction log to note what's in flight and what's not, >>> so if the snapshot system is including sstables being written (from flush, >>> from compaction, or from streaming), those aren't final and should be >>> skipped. >>> >>> >>> >>> >>> On Fri, Mar 18, 2022 at 11:46 AM James Brown <jbr...@easypost.com> >>> wrote: >>> >>>> We use the boring combo of cassandra snapshots + tar to backup our >>>> cassandra nodes; every once in a while, we'll notice tar failing with the >>>> following: >>>> >>>> tar: >>>> data/addresses/addresses-eb0196100b7d11ec852b1541747d640a/snapshots/backup20220318183708/nb-167-big-Data.db: >>>> file changed as we read it >>>> >>>> I find this a bit perplexing; what would cause an sstable inside a >>>> snapshot to change? The only thing I can think of is an incremental repair >>>> changing the "repaired_at" flag on the sstable, but it seems like that >>>> should "un-share" the hardlinked sstable rather than running the risk of >>>> mutating a snapshot. >>>> >>>> >>>> James Brown >>>> Cassandra admin @ easypost.com >>>> >>> >> >>
