I was perhaps a bit snarky with you there Marc; my apologies. There's a history of some tension between Cassandra and Scylla and a user coming from an unrelated community knowingly asking for free support / time / energy from an unrelated project while holding back that context rubbed me the wrong way.
In the future I'd advise leading with your context rather than holding back on "having a confession to make". Also, for posterity: a quick google of "Scylla Recycled commit logs" turns up this as the first response: https://github.com/scylladb/scylladb/issues/11184 On Wed, Jul 2, 2025, at 4:26 AM, Dmitry Konstantinov wrote: > Hi Marc, > > The recycled commit logs functionality was used in very old versions of > Cassandra, but it was removed in version 2.2.0 back in 2015 (so this logic > was removed 10 years ago, and understandably, no one wants to do > archaeological research). The currently supported versions start from 4.0.x. > > The idea behind recycled logs was to reuse commit log files to reduce file > system overhead, but in practice, it didn’t work well. It caused issues and > made the implementation unnecessarily complex, so the feature was eventually > removed. > > > Here’s a good summary article about the Cassandra commit log design, which > also includes a section on recycled logic ("Segment Recycling"): > https://cassandra.apache.org/_/blog/Learn-How-CommitLog-Works-in-Apache-Cassandra.html > > However, this knowledge about Cassandra likely won’t help with your current > issue — there’s no guarantee that ScyllaDB shares a similar design in this > area, and any bugs will be specific to ScyllaDB. So, I think the best next > step for you is to contact the ScyllaDB community directly. > > > You can also check their existing GitHub issues — for example, here’s one > that describes similar symptoms: > https://github.com/scylladb/scylladb/issues/11184 > > > Regards, > Dmitry > > > > On Wed, 2 Jul 2025 at 07:57, Marc Hoppins <marc.hopp...@eset.com> wrote: >> SO CASSANDRA NEVER HAD RECYCLED COMMIT LOGS? If not then I apologise for >> wasting everyone’s time. However if, for previous versions, recycled >> commitlogs were a part of Cassandra then thank you fr not sharing the >> knowledge of a Cassandra item.____ >> __ __ >> Time to unsubscribe____ >> __ __ >> *From:* Josh McKenzie <jmcken...@apache.org> >> *Sent:* Tuesday, July 1, 2025 1:47 PM >> *To:* user@cassandra.apache.org >> *Subject:* Re: Recycled-Commitlogs____ >> __ __ >> EXTERNAL____ >>> Can anyone explain WHAT they are?____ >> Yes Marc. The Scylla community. That's what we're trying to tell you.____ >> __ __ >> As far as anyone on this list seems to think, this isn't related to Apache >> Cassandra.____ >> __ __ >> On Tue, Jul 1, 2025, at 1:54 AM, Marc Hoppins wrote:____ >>> That aside. Can anyone explain WHAT they are? If they were done away with >>> in Cassandra then they must have been surplus to requirements. In which >>> case, why have them originally? They must have been there for some >>> reason.____ >>> >>> ____ >>> >>> *From:* Josh McKenzie <jmcken...@apache.org> >>> *Sent:* Monday, June 30, 2025 4:16 PM >>> *To:* user@cassandra.apache.org >>> *Subject:* Re: Recycled-Commitlogs____ >>> >>> ____ >>> >>> EXTERNAL____ >>> >>>> As it is (generally) Cassandra compatible I naturally assumed that these >>>> items were in both applications.____ >>>> >>> For future reference - it's "generally CQL API compatible". That's the >>> extent of it.____ >>> >>> ____ >>> >>> It's analogous to driving a make/model of one car and taking it to a >>> completely different unrelated dealer for maintenance because they're both >>> cars. Just because the interface to use them (steering wheel, doors, >>> engine, 4 tires) is broadly the same, the internals are wildly >>> different.____ >>> >>> ____ >>> >>> On Sat, Jun 28, 2025, at 11:56 PM, Jeff Jirsa wrote:____ >>> >>>> Yea we’re not gonna be able to help you____ >>>> >>>> ____ >>>> >>>> This sounds like a software defect but it’s not cassandra so we really do >>>> much ____ >>>> >>>> ____ >>>> >>>> On 2025/06/27 13:13:17 Marc Hoppins wrote:____ >>>> >>>> > Well, I do have a confession to make. It is actually scyllaDB and the >>>> > latest version. As it is (generally) Cassandra compatible I naturally >>>> > assumed that these items were in both applications.____ >>>> >>>> > ____ >>>> >>>> > Marc____ >>>> >>>> > ____ >>>> >>>> > From: Jeff Jirsa <jji...@gmail.com>____ >>>> >>>> > Sent: Thursday, June 26, 2025 7:35 PM____ >>>> >>>> > To: user@cassandra.apache.org____ >>>> >>>> > Cc: user@cassandra.apache.org____ >>>> >>>> > Subject: Re: Recycled-Commitlogs____ >>>> >>>> > ____ >>>> >>>> > EXTERNAL____ >>>> >>>> > What version of cassandra is this?____ >>>> >>>> > ____ >>>> >>>> > Recycling segments was a thing from like 1.1 to 2.2 but really very >>>> > different in modern versions (and cdc / point in time backup mirrors >>>> > some of the concepts around hanging onto segments)____ >>>> >>>> > ____ >>>> >>>> > Knowing the version would be super helpful though____ >>>> >>>> > ____ >>>> >>>> > Is this … 1.2? 2.0?____ >>>> >>>> > ____ >>>> >>>> > ____ >>>> >>>> > ____ >>>> >>>> > On Jun 26, 2025, at 1:22 AM, guo Maxwell >>>> > <cclive1...@gmail.com<mailto:cclive1...@gmail.com>> wrote:____ >>>> >>>> > ____ >>>> >>>> > I guess it comes from the archive of commitlogs ，just guess~~~____ >>>> >>>> > ____ >>>> >>>> > But I think we need the cassandra's version and commitlog's >>>> > configuration in cassandra.yaml, and commitlog_archiving.properties to >>>> > determine this.____ >>>> >>>> > ____ >>>> >>>> > Marc Hoppins <marc.hopp...@eset.com<mailto:marc.hopp...@eset.com>> >>>> > 于2025年6月26日周四 16:08写道：____ >>>> >>>> > Hi,____ >>>> >>>> > ____ >>>> >>>> > I am not a data person but a Linux admin. One of our nodes has >>>> > thousands of____ >>>> >>>> > ____ >>>> >>>> > -rw-r--r-- 1 root root 33554432 Jun 24 15:11 >>>> > Recycled-CommitLog-2-67041997483.log____ >>>> >>>> > ____ >>>> >>>> > hanging around. Eventually they fill the filesystem. I have searched >>>> > around and can find no mention of these recycled commits.____ >>>> >>>> > ____ >>>> >>>> > Can anyone explain what they are for? Can I purge these in some >>>> > graceful fashion with a service restart, a simple deletion, or a >>>> > complete drain/restart of the node?____ >>>> >>>> > ____ >>>> >>>> > Thanks____ >>>> >>>> > ____ >>>> >>>> > Marc____ >>>> >>>> > ____ >>>> >>>> ____ >>>> >>> ____ >>> >> __ __ > > > -- > Dmitry Konstantinov
