[Dovecot] XFS vs EXT4 for mail storage

[Luigi Rosa]

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Charles Marcus said the following on 02/05/2013 13:16:

> So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS with
> just the defaults? Or XFS with one or more tuned parameters?

Expecially when you are working in virtual environments, keep in mind the
concept of "I/O cascading"

The bottleneck of virtual environment are often IOPS (I/O per second), so a VM
that has a light footprint of IOPS will have a better performance.

The I/O cascading is in essence the muptiplying factor of each disk write at
application level. Consider a SQL UPDATE statement: you have date written on
database and trasaction log. Each file will have its mtime updated. If the
underlying file system is transactional you will have double writes for actual
file and transaction log... And so on.

The first and obvious advice (quite a default nowdays with SSD storage) is to
mount the FS with noatime. But I think that is obvius as "do backups".





Ciao,
luigi

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