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WiredTIger pre allocated journal files behaviour

Hi,

I am working a file system based snapshot solution. While copying the snapshot, few files like WiredTigerPrepLog.* files are NOT found and the copy fails. Can someone confirm if we really need these pre-allocated journal files to be copied ? can it be skipped ? are they needed for bringing up the mongods later from the restored content.

Thanks
Saamaja

Hi Saamaja,

Basically when taking a backup using snapshot, you should treat the whole dbPath as a single unit, including all the preplog files, and any file that seems to have no bearing on your data. This is to ensure that WiredTiger is starting from a known state, and would lower the risk of things going wrong with the restore.

Best regards,
Kevin