Обсуждение: Does btrfs on Linux have a negative performance impact for PostgreSQL 13?

I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near releasing my
project.I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know if it would
havea major performance impact? 

Simon.

On Sat, Apr 24, 2021 at 06:27:08PM +0000, Simon Connah wrote:
> I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near releasing
myproject. I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know if it
wouldhave a major performance impact?
 

Is there some reason the question is specific to postgres13 , or did you just
say that because it's your development target for your project.

I think it almost certainly depends more on your project than on postgres 13.

It may well be that performance is better under btrfs, maybe due to compression
or COW.  But you'd have to test what you're doing to find out - and maybe write
up the results.

Also, it's very possible that btfs performs better for (say) report queries,
but worse for data loading.  Maybe you care more about reporting, but that's
not true for everyone.

-- 
Justin

> On Apr 24, 2021, at 11:27, Simon Connah <simon.n.connah@protonmail.com> wrote:
>
> I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near releasing
myproject. I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know if it
wouldhave a major performance impact? 

This is a few years old, but Tomas Vondra did a presentation comparing major Linux file systems for PostgreSQL:

    https://www.slideshare.net/fuzzycz/postgresql-on-ext4-xfs-btrfs-and-zfs

On 4/24/21 9:02 PM, Christophe Pettus wrote:
> 
> 
>> On Apr 24, 2021, at 11:27, Simon Connah <simon.n.connah@protonmail.com> wrote:
>>
>> I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near releasing
myproject. I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know if it
wouldhave a major performance impact?
 
> 
> This is a few years old, but Tomas Vondra did a presentation comparing major Linux file systems for PostgreSQL:
> 
>     https://www.slideshare.net/fuzzycz/postgresql-on-ext4-xfs-btrfs-and-zfs
> 

That talk was ages ago, though. The general conclusions may be still 
valid, but maybe btrfs improved a lot - I haven't done any testing since 
then. Not sure about durability, but there are companies using btrfs so 
perhaps it's fine - not sure.

Arguably, a lot of this also depends on the exact workload - the issues 
I saw with btrfs were with OLTP stress test, it could have performed 
much better with other workloads.


regards
Tomas

On 24/04/21, Christophe Pettus (xof@thebuild.com) wrote:
> > On Apr 24, 2021, at 11:27, Simon Connah <simon.n.connah@protonmail.com> wrote:
> > 
> > I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near releasing
myproject. I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know if it
wouldhave a major performance impact?
 
> 
> This is a few years old, but Tomas Vondra did a presentation comparing major Linux file systems for PostgreSQL:
> 
>     https://www.slideshare.net/fuzzycz/postgresql-on-ext4-xfs-btrfs-and-zfs

I guess btrfs and zfs on linux performance might have improved somewhat since Tomas' analysis in 2015.

Personally I've been a keen personal user of btrfs for over 5 years for its snapshot support, transparent compression
andbitrot detection. However I can't think of a reason to use it for a production server. It's slower than ext4 and
xfs,postgresql's dumping and streaming are probably better bets than snapshots for backup, and relatively few others
arelikely to be comfortable administering it. But maybe I'm missing something.
 

Phoronix run btrfs benchmarks from time-to-time. See https://www.phoronix.com/scan.php?page=search&q=Btrfs

Rory

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Saturday, April 24th, 2021 at 21:03, Rory Campbell-Lange <rory@campbell-lange.net> wrote:

> On 24/04/21, Christophe Pettus (xof@thebuild.com) wrote:
>

> > > On Apr 24, 2021, at 11:27, Simon Connah simon.n.connah@protonmail.com wrote:
> > >

> > > I'm curious, really. I use btrfs as my filesystem on my home systems and am setting up a server as I near
releasingmy project. I planned to use btrfs on the server, but it got me thinking about PostgreSQL 13. Does anyone know
ifit would have a major performance impact? 
> >

> > This is a few years old, but Tomas Vondra did a presentation comparing major Linux file systems for PostgreSQL:
> >

> > https://www.slideshare.net/fuzzycz/postgresql-on-ext4-xfs-btrfs-and-zfs
>

> I guess btrfs and zfs on linux performance might have improved somewhat since Tomas' analysis in 2015.
>

> Personally I've been a keen personal user of btrfs for over 5 years for its snapshot support, transparent compression
andbitrot detection. However I can't think of a reason to use it for a production server. It's slower than ext4 and
xfs,postgresql's dumping and streaming are probably better bets than snapshots for backup, and relatively few others
arelikely to be comfortable administering it. But maybe I'm missing something. 
>

> Phoronix run btrfs benchmarks from time-to-time. See https://www.phoronix.com/scan.php?page=search&q=Btrfs
>

> Rory

I should have been more explicit in my original post. I use OpenSUSE Tumbleweed and btrfs is the default filesystem. I
alsobelieve SUSE Linux Enterprise Server uses btrfs as their default which seems to indicate that at least one
enterprise-gradeLinux distribution trusts btrfs for their default install. 

I'd love to do some performance testing myself but the only way I could do it would be inside virtual machines which
wouldmake the numbers meaningless. I'll certainly do some reading on the subject and look at that presentation that was
mentioned.