[systemd-devel] Antw: Re: [EXT] Re: consider dropping defrag of journals on btrfs

[Ulrich Windl]

>>> Phillip Susi <phill at thesusis.net> schrieb am 10.02.2021 um 20:39 in Nachricht
<878s7v6759.fsf at vps.thesusis.net>:

> Chris Murphy writes:
> 
>> It's not interleaving. It uses delayed allocation to make random
>> writes into sequential writes. It's tries harder to keep file blocks
> 
> Yes, and when you do that, you are inverleaving data from multiple files
> into a single stream, which you really shouldn't be doing.  IIRC, XFS
> has special io streaming modes specifically designed to *prevent* this
> from happening and record multiple video streams simultaniously to
> different parts of the disk to keep them from being fragmented to hell
> like that.

I wonder: Would this discussion benefit if some blocktrace graphics were shown to prove the claims?

(Several years ago I did that to examine our Database I/O. See example)

Regards,
Ulrich



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