# Files - What are they? **URL:** \ **Category:** Percona XtraDB Cluster 8.x\ **Created:** [January 20, 2022, 4:50pm UTC](https://forums.percona.com/t/files-what-are-they/14025 "2022-01-20T16:50:39Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![meyerder](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/meyerder/32/16994_2.png) [@meyerder](https://forums.percona.com/u/meyerder)\ **Post date:** [January 20, 2022, 4:50pm UTC](https://forums.percona.com/t/files-what-are-they/14025/1 "2022-01-20T16:50:39Z")
I sometimes have an issue where my cluster freezes and items just stop processing. I am aware of what the bug is and waiting for the new release to account for it (Documented bug) Today I saw something a bit weird… I know the exact time where things started to back up on the system About 30 minutes later I had to crash the node to get things to fail over quicker. When I reviewed the issue about 30 minutes prior (around the actual time where things started to go south) these files were created in my data dir. What are they? How do I read them? #:/app/mysql/data # ls -la | grep 20 drwxr-xr-x 45 mysql mysql 4096 Jan 20 08:57 . -rw-r----- 1 mysql mysql 67108864 Jan 20 08:32 0xaa5aafb1\_data.000000 -rw-r----- 1 mysql mysql 67108864 Jan 20 08:33 0xaa5abdb3\_data.000000 -rw-r----- 1 mysql mysql 67108864 Jan 20 08:33 0xaa5ae87c\_data.000000 -rw-r----- 1 mysql mysql 67108864 Jan 20 08:34 0xaa5af6a4\_data.000000 #:/app/mysql/data # file 0xaa5af6a4\_data.000000 0xaa5af6a4\_data.000000: data ---
**Author:** ![vadimtk](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/vadimtk/32/9528_2.png) [@vadimtk](https://forums.percona.com/u/vadimtk)\ **Post date:** [January 23, 2022, 5:34pm UTC](https://forums.percona.com/t/files-what-are-they/14025/2 "2022-01-23T17:34:38Z")
Likely you see gcache files > **[Percona Software Documentation](https://docs.percona.com/percona-xtradb-cluster/5.7/manual/gcache_record-set_cache_difference.html)** > > .container-box-download { justify-content: flex-start; } .container-button-learn-more { margin-bottom: 10px; } .logo-server-home { background: url(/img/product-logos/sprite.png) You do not need to read them, as they are only for internal usage ---
**Author:** ![meyerder](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/meyerder/32/16994_2.png) [@meyerder](https://forums.percona.com/u/meyerder)\ **Post date:** [January 24, 2022, 2:59pm UTC](https://forums.percona.com/t/files-what-are-they/14025/3 "2022-01-24T14:59:01Z")
@vadimtk Thank you… I was unable to find via google what these files were. I wonder if this might be related to my intermittent crashes as according to PMM all transactions appear to have “stopped” before these files were created. I am not sure if this is the cause or the effect… Initially, I was under the assumption that my stops were related to PXC3706 (or maybe 3776?) which ?may? be resolved in 8.0.26-16.1 (see above post in the 8.0.26 thread) What I noticed was a large jump in the Avg Replication delay (the delay was on the Writer I send all to one system none of the others get much traffic. and is a 5 node Cluster geographically diverse with three in one data center) According to pmm no flow control items were started or anything else that jumps out at me… and I saw no abnormal locks or other items… just it “stopped” If what I am reading is correct I should be able to review the binlogs and determine the large transaction that may have caused this and ask them to set a streaming session? \*\*Note as I have slow query logs enabled and did not see anything at the time I am guessing that cause I had to crash it the query did not show up (As it didn’t finish) I also saw nothing in the binlog (but now I know what to look for more) Your thoughts on if this is/was a cause or effect of the system stopping processing as writes (reads kept working) \*\*Note I need to enable the wait event analyses for the wsrep conditions as right now my logs appear to be empty for those graphs… ![image](https://us1.discourse-cdn.com/flex019/uploads/percona1/original/2X/3/3a75960f71b83c73b83b6afbe2dad93e6c426a71.png) ![image](https://us1.discourse-cdn.com/flex019/uploads/percona1/original/2X/7/73d85329fd4790385cdd589f4f06c09d5b0e5e8c.png)