Re: BTRFS and databases

[Hugo Mills <hugo@carfax.org.uk>]

[-- Attachment #1: Type: text/plain, Size: 1745 bytes --]

On Wed, Aug 01, 2018 at 05:45:15AM +0200, MegaBrutal wrote:
> I know it's a decade-old question, but I'd like to hear your thoughts
> of today. By now, I became a heavy BTRFS user. Almost everywhere I use
> BTRFS, except in situations when it is obvious there is no benefit
> (e.g. /var/log, /boot). At home, all my desktop, laptop and server
> computers are mainly running on BTRFS with only a few file systems on
> ext4. I even installed BTRFS in corporate productive systems (in those
> cases, the systems were mainly on ext4; but there were some specific
> file systems those exploited BTRFS features).
> 
> But there is still one question that I can't get over: if you store a
> database (e.g. MySQL), would you prefer having a BTRFS volume mounted
> with nodatacow, or would you just simply use ext4?

   Personally, I'd start with btrfs with autodefrag. It has some
degree of I/O overhead, but if the database isn't performance-critical
and already near the limits of the hardware, it's unlikely to make
much difference. Autodefrag should keep the fragmentation down to a
minimum.

   Hugo.

> I know that with nodatacow, I take away most of the benefits of BTRFS
> (those are actually hurting database performance – the exact CoW
> nature that is elsewhere a blessing, with databases it's a drawback).
> But are there any advantages of still sticking to BTRFS for a database
> albeit CoW is disabled, or should I just return to the old and
> reliable ext4 for those applications?
> 
> 
> Kind regards,
> MegaBrutal

-- 
Hugo Mills             | In theory, theory and practice are the same. In
hugo@... carfax.org.uk | practice, they're different.
http://carfax.org.uk/  |
PGP: E2AB1DE4          |

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]