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· Jul 27, 2022

IRIS when is it safe to delete Journals

#InterSystems IRIS

Hi,

I have a question about deleting journals at the OS level(Linux) without corrupting the IRIS DB or it’s mirror copies.

The reason for deleting journals is the filesystem it lives on frequently fills up. 

I don't have enough disk space to further expand the journal filesystems.

When the journal filesystem fills up then the application stops.

 

I have the following IRIS nodes(mirror status)

LIVETC01            Backup

LIVETC02            Primary

LIVEDR                Async Copy        **OFFLINE**

ARBITER

 

LIVEDR is currently offline but IRIS software has been installed.

I checked inside Mirror Monitor that LIVETC01 has "caught up" status

To “refresh” LIVEDR DB I have:

  1. Stopped IRIS on LIVETC01 @ 25/07 22:30
  2. Copy IRIS.DAT files(OS) from LIVETC01 to LIVEDR for all databases
  3. Start IRIS on LIVETC01 @ 26/07 11:00
  4. Start IRIS on LIVEDR @ 26/07 11:00

 

Journal Switch occurs at 00:00 every day.

 

I think it is safe to delete journals on LIVETC02 created prior to 24/07 23:59:59 as there should be no

transactions spanning journal files because of journal switch of 25/07 @ 00:00

 

I think it is safe to delete all journals on LIVETC01.

 

Do you think it is safe to delete these journals?

Thanks for any help

Discussion (5)1
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Vic Sun · Jul 27, 2022

As Alexander said, I would not recommend deleting journals from the OS. Worst case you make mirror syncing or transactions fail, or less bad but annoying you can orphan journals from the instance's record.

Journals are an important part of backup recovery as well (though a mirror covers some of that recovery role). How many days of journals are you keeping such that you fill your disk?

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Yaron Munz · Aug 4, 2022

You have to distinguish between "journals" and "mirror-journals" files. the 1st are to ensure any instance DB integrity (DB corruption) in case of a failure. The 2nd are you ensure proper mirror "failover" and any A-Sync members.

When LIVETC01 (as a Backup) is "catch up" its a good source to copy .DAT files to the LIVEDR.
It is also safe to delete its mirror-journals.
The steps you did to catch up the LIVEDR are correct. (I assume you did "activate" & "catch up" after that in LIVEDR)

After the IRIS.DAT copy (of all DBs in mirror) from LIVETC01 to LIVEDR and both are "catch up" - It is safe to delete mirror-journals up to the point of the copy from your primary LIVETC02

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