As much as sstable files are immutable, there are operations that can delete them, such as compactions (merges) and upgrades (upgradesstables - you possibly ran this in your upgrade).
Even though snapshots are hardlinks, when the original sstable file get deleted, it will actually behave like a copy of the old file as it will keep pointing to the old inodes. Luciano Greiner On Thu, Mar 13, 2025 at 11:23 PM William Crowell <wcrow...@perforce.com> wrote: > Luciano, > > > > That is very possible. Any reasons why the increased disk space from > version 3 to 4? Did anything in particular change that would affect disk > space? > > > > Thank you for your reply, > > > > William Crowell > > > > *From: *Luciano Greiner <luciano.grei...@gmail.com> > *Date: *Thursday, March 13, 2025 at 10:21 PM > *To: *user@cassandra.apache.org <user@cassandra.apache.org> > *Cc: *William Crowell <wcrow...@perforce.com> > *Subject: *Re: Increased Disk Usage After Upgrading From Cassandra 3.x.x > to 4.1.3 > > You don't often get email from luciano.grei...@gmail.com. Learn why this > is important <https://aka.ms/LearnAboutSenderIdentification> > > Haven't you forgot to clean some snapshots ? > > > > Luciano Greiner > > > > > > > > On Thu, Mar 13, 2025 at 11:18 PM William Crowell via user < > user@cassandra.apache.org> wrote: > > Hi, > > > > Is this mailing list still active? > > > > Thanks. > > > > *From: *William Crowell via user <user@cassandra.apache.org> > *Date: *Wednesday, March 12, 2025 at 4:42 PM > *To: *user@cassandra.apache.org <user@cassandra.apache.org> > *Cc: *William Crowell <wcrow...@perforce.com> > *Subject: *Re: Increased Disk Usage After Upgrading From Cassandra 3.x.x > to 4.1.3 > > I also forgot to include we do compaction once a week. > > > > Hi. A few months ago, I upgraded a single node Cassandra instance from > version 3 to 4.1.3. This instance is not very large with about 15 to 20 > gigabytes of data on version 3, but after the update it has went > substantially up to over 100gb. I do a compaction once a week and take a > snapshot, but with the increase in data it makes the compaction a much > lengthier process. I also did a sstableupate as part of the upgrade. Any > reason for the increased size of the database on the file system? > > > > I am using the default STCS compaction strategy. My “nodetool cfstats” on > a heavily used table looks like this: > > > > Keyspace : xxxxxxxx > > Read Count: 48089 > > Read Latency: 12.52872569610514 ms > > Write Count: 1616682825 > > Write Latency: 0.0067135265490310386 ms > > Pending Flushes: 0 > > Table: sometable > > SSTable count: 13 > > Old SSTable count: 0 > > Space used (live): 104005524836 > > Space used (total): 104005524836 > > Space used by snapshots (total): 0 > > Off heap memory used (total): 116836824 > > SSTable Compression Ratio: 0.566085855123187 > > Number of partitions (estimate): 14277177 > > Memtable cell count: 81033 > > Memtable data size: 13899174 > > Memtable off heap memory used: 0 > > Memtable switch count: 13171 > > Local read count: 48089 > > Local read latency: NaN ms > > Local write count: 1615681213 > > Local write latency: 0.005 ms > > Pending flushes: 0 > > Percent repaired: 0.0 > > Bytes repaired: 0.000KiB > > Bytes unrepaired: 170.426GiB > > Bytes pending repair: 0.000KiB > > Bloom filter false positives: 125 > > Bloom filter false ratio: 0.00494 > > Bloom filter space used: 24656936 > > Bloom filter off heap memory used: 24656832 > > Index summary off heap memory used: 2827608 > > Compression metadata off heap memory used: 89352384 > > Compacted partition minimum bytes: 73 > > Compacted partition maximum bytes: 61214 > > Compacted partition mean bytes: 11888 > > Average live cells per slice (last five minutes): NaN > > Maximum live cells per slice (last five minutes): 0 > > Average tombstones per slice (last five minutes): NaN > > Maximum tombstones per slice (last five minutes): 0 > > Dropped Mutations: 0 > > Droppable tombstone ratio: 0.04983 > > > > > > *This e-mail may contain information that is privileged or confidential. > If you are not the intended recipient, please delete the e-mail and any > attachments and notify us immediately.* > > > > *CAUTION:* This email originated from outside of the organization. Do not > click on links or open attachments unless you recognize the sender and know > the content is safe. > > > > > > *This e-mail may contain information that is privileged or confidential. > If you are not the intended recipient, please delete the e-mail and any > attachments and notify us immediately.* > > > > *CAUTION:* This email originated from outside of the organization. Do not > click on links or open attachments unless you recognize the sender and know > the content is safe. > > > > > > *This e-mail may contain information that is privileged or confidential. > If you are not the intended recipient, please delete the e-mail and any > attachments and notify us immediately.* > > > > > > *CAUTION:* This email originated from outside of the organization. Do not > click on links or open attachments unless you recognize the sender and know > the content is safe. > > > > This e-mail may contain information that is privileged or confidential. If > you are not the intended recipient, please delete the e-mail and any > attachments and notify us immediately. > >
