# Running pt-online-schema-change increases the size of the file on disk **URL:** \ **Category:** Percona XtraDB Cluster 5.x\ **Created:** [November 10, 2021, 1:41pm UTC](https://forums.percona.com/t/running-pt-online-schema-change-increases-the-size-of-the-file-on-disk/12939 "2021-11-10T13:41:45Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![ravimalghan](https://avatars.discourse-cdn.com/v4/letter/r/c4cdca/32.png) [@ravimalghan](https://forums.percona.com/u/ravimalghan)\ **Post date:** [November 10, 2021, 1:41pm UTC](https://forums.percona.com/t/running-pt-online-schema-change-increases-the-size-of-the-file-on-disk/12939/1 "2021-11-10T13:41:45Z")
I have been using pt-online-schema-change to reduce the file size on disk for a table that has lot of deletes. It has worked as expected for a long time. I have not updated anything. For my last 4 runs, the file size seems to be growing everytime I run. The number of rows is about the same. I started with 141G. Ran the pt-online-schema-change about 4 times. When I just ran it now, the file size on disk went from 191G to 200G. All the runs are completing successfully (triggers dopped, the \_\ dropped). Why would this be happening? > pt-online-schema-change --version > pt-online-schema-change 3.0.12 ---
**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\ **Post date:** [November 11, 2021, 3:01am UTC](https://forums.percona.com/t/running-pt-online-schema-change-increases-the-size-of-the-file-on-disk/12939/2 "2021-11-11T03:01:50Z")
Can you give us more information? How are you running pt-osc? Have you confirmed free space before running and after running? Are you watching the size of the shadow table as it is being populated? ---
**Author:** ![ravimalghan](https://avatars.discourse-cdn.com/v4/letter/r/c4cdca/32.png) [@ravimalghan](https://forums.percona.com/u/ravimalghan)\ **Post date:** [February 25, 2022, 2:30pm UTC](https://forums.percona.com/t/running-pt-online-schema-change-increases-the-size-of-the-file-on-disk/12939/3 "2022-02-25T14:30:37Z")
Here’s how I am running the command. File size before I ran the command ```auto cd /export/apps/moogdata/var; find ./ -type f -exec du -Sh {} + | sort -rh | head -n 20 160G ./lib/mysql/historic_moogdb/snapshots.ibd ``` ```auto pt-online-schema-change --chunk-size 20000 --user=root --ask-pass --progress time,10 --socket=/export/apps/moogdata/var/lib/mysql/mysql.sock --print --nocheck-unique-key-change --no-check-alter --execute --critical-load Threads_running=100 --alter "ENGINE=InnoDB" h=localhost,D=historic_moogdb,t=snapshots ``` It completes successfully ```auto Copying `historic_moogdb`.`snapshots`: 99% 00:13 remain Copying `historic_moogdb`.`snapshots`: 99% 00:05 remain 2022-02-25T09:12:20 Copied rows OK. 2022-02-25T09:12:20 Analyzing new table... 2022-02-25T09:12:20 Swapping tables... RENAME TABLE `historic_moogdb`.`snapshots` TO `historic_moogdb`.`_snapshots_old`, `historic_moogdb`.`_snapshots_new` TO `historic_moogdb`.`snapshots` 2022-02-25T09:12:20 Swapped original and new tables OK. 2022-02-25T09:12:20 Dropping old table... DROP TABLE IF EXISTS `historic_moogdb`.`_snapshots_old` 2022-02-25T09:13:00 Dropped old table `historic_moogdb`.`_snapshots_old` OK. 2022-02-25T09:13:00 Dropping triggers... DROP TRIGGER IF EXISTS `historic_moogdb`.`pt_osc_historic_moogdb_snapshots_del` DROP TRIGGER IF EXISTS `historic_moogdb`.`pt_osc_historic_moogdb_snapshots_upd` DROP TRIGGER IF EXISTS `historic_moogdb`.`pt_osc_historic_moogdb_snapshots_ins` 2022-02-25T09:13:00 Dropped triggers OK. Successfully altered `historic_moogdb`.`snapshots`. ``` File size went to 240G ```auto cd /export/apps/moogdata/var; find ./ -type f -exec du -Sh {} + | sort -rh | head -n 20 240G ./lib/mysql/historic_moogdb/snapshots.ibd ``` ---
**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\ **Post date:** [February 25, 2022, 4:33pm UTC](https://forums.percona.com/t/running-pt-online-schema-change-increases-the-size-of-the-file-on-disk/12939/4 "2022-02-25T16:33:06Z")
I would use the innodb\_ruby tools to count the number of data, index, and free pages before and after. Because this is row-by-row copying, the new table may be attempting to balance the pages to favor more intra-page free space for new INSERTs rather than make pages as compact as can be. Generally InnoDB will fill data pages only to 50 percent initially. This results in a naturally larger disk footprint. Maybe check out this parameter [MySQL :: MySQL 5.7 Reference Manual :: 14.15 InnoDB Startup Options and System Variables](https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html#sysvar_innodb_fill_factor)