[plug] Filesystems for lots of inodes

[Chris Hoy Poy]

Hi all,

XFS has an online "defragment" which works by copying entire files to "free
contiguous space" - so as long as you have free contiguous space, it will
keep up. You can tell it to run for like an hour or two a night (watch it
doesn't clash with your backups). There are various bugs around where files
will get truncated.

Zfs is okay but tbh it will suffer from the same issues going forward
(fragmentation!).

Btrfs - wouldn't bother

I think ext4 has an online defragment too, but I haven't played with it in
production.

In general, XFS is my go-to, and we do use it a lot. I have used XFS for
this purpose for over a decade in various implementations :-)

Most file systems suck horribly if they have less then 20% capacity
(obviously) but over time, when used as a backup and trimmed, you can't
avoid having to copy files to defrag them.

Cheers
/Chris

On Sat, 4 Jan 2020, 5:10 pm Brad Campbell, <brad at fnarfbargle.com> wrote:

> Woooo. It finished
>
> srv:/mnt# time du -hcs *
> 2.3M    30seafield_home
> ..... <snip> .....
> 3.3T    total
>
> real    945m18.422s
> user    2m35.516s
> sys     14m13.933s
>
> Only 15 hours. Now lets see how long a dump/restore takes.
>
> To put it in perspective. Raw sequential on this array is ~500MB/s. It
> took a couple of hours to clone the entire filesystem using dd.
>
> --
> An expert is a person who has found out by his own painful
> experience all the mistakes that one can make in a very
> narrow field. - Niels Bohr
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