databases should be created with chattr +C

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4 participants
  • Danny Milosavljevic
  • Efraim Flashner
  • Ludovic Courtès
  • Rutger Helling
Owner
unassigned
Submitted by
Efraim Flashner
Severity
normal
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Efraim Flashner wrote on 12 Dec 2017 12:46
(address . bug-guix@gnu.org)
20171212114608.GB1873@macbook41
We support running GuixSD on top of btrfs, and the prevailing wisdom is
to mark databases (sqlite, postgresql, etc.) as 'chattr +C', that is, as
not copy-on-write. It is honored under ext4, but it shouldn't cause any
changes.

--
Efraim Flashner <efraim@flashner.co.il> ????? ?????
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Confidentiality cannot be guaranteed on emails sent or received unencrypted
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R
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Rutger Helling wrote on 13 Dec 2017 09:50
(address . 29675@debbugs.gnu.org)(address . efraim@flashner.co.il)
faea3e29b291d7ff118b54880b7b8124@mykolab.com
This should also be done with virtual machine images.
D
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Danny Milosavljevic wrote on 13 Dec 2017 15:40
(name . Efraim Flashner)(address . efraim@flashner.co.il)(address . 29675@debbugs.gnu.org)
20171213154003.29024f01@scratchpost.org
Hi Efraim,

On Tue, 12 Dec 2017 13:46:08 +0200
Efraim Flashner <efraim@flashner.co.il> wrote:

Toggle quote (5 lines)
> We support running GuixSD on top of btrfs, and the prevailing wisdom is
> to mark databases (sqlite, postgresql, etc.) as 'chattr +C', that is, as
> not copy-on-write. It is honored under ext4, but it shouldn't cause any
> changes.

It sounds reasonable to do that - but I don't think that relational databases are managed by the Guix store. Rather they are in /var or in the home directory. Long story short, it would make sense for Postgres and Sqlite upstream to do the chattr +C, if they don't already do it.
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Ludovic Courtès wrote on 20 Dec 2017 14:12
(name . Danny Milosavljevic)(address . dannym@scratchpost.org)
87efnpy248.fsf@gnu.org
Hello,

Danny Milosavljevic <dannym@scratchpost.org> skribis:

Toggle quote (10 lines)
> On Tue, 12 Dec 2017 13:46:08 +0200
> Efraim Flashner <efraim@flashner.co.il> wrote:
>
>> We support running GuixSD on top of btrfs, and the prevailing wisdom is
>> to mark databases (sqlite, postgresql, etc.) as 'chattr +C', that is, as
>> not copy-on-write. It is honored under ext4, but it shouldn't cause any
>> changes.
>
> It sounds reasonable to do that - but I don't think that relational databases are managed by the Guix store. Rather they are in /var or in the home directory. Long story short, it would make sense for Postgres and Sqlite upstream to do the chattr +C, if they don't already do it.

I agree.

Efraim, unless we have a specific example, I’m inclined to close it as
“not-a-bug”, with the understanding that it’s an upstream issue rather
than something GuixSD-specific.

How does that sound?

Ludo’.
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Efraim Flashner wrote on 20 Dec 2017 14:31
(name . Ludovic Courtès)(address . ludo@gnu.org)
20171220133112.GA16642@macbook41
On Wed, Dec 20, 2017 at 02:12:39PM +0100, Ludovic Courtès wrote:
Toggle quote (24 lines)
> Hello,
>
> Danny Milosavljevic <dannym@scratchpost.org> skribis:
>
> > On Tue, 12 Dec 2017 13:46:08 +0200
> > Efraim Flashner <efraim@flashner.co.il> wrote:
> >
> >> We support running GuixSD on top of btrfs, and the prevailing wisdom is
> >> to mark databases (sqlite, postgresql, etc.) as 'chattr +C', that is, as
> >> not copy-on-write. It is honored under ext4, but it shouldn't cause any
> >> changes.
> >
> > It sounds reasonable to do that - but I don't think that relational databases are managed by the Guix store. Rather they are in /var or in the home directory. Long story short, it would make sense for Postgres and Sqlite upstream to do the chattr +C, if they don't already do it.
>
> I agree.
>
> Efraim, unless we have a specific example, I’m inclined to close it as
> “not-a-bug”, with the understanding that it’s an upstream issue rather
> than something GuixSD-specific.
>
> How does that sound?
>
> Ludo’.

My intention was that after creating the database in /var that it should
get 'chattr +C file', but it actually looks like people are divided
between less fragmentation from not CoW for the database or more
recovery options from having it CoW and the checksumming, so closing it
and leaving it alone for now seems best.

--
Efraim Flashner <efraim@flashner.co.il> ????? ?????
GPG key = A28B F40C 3E55 1372 662D 14F7 41AA E7DC CA3D 8351
Confidentiality cannot be guaranteed on emails sent or received unencrypted
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Ludovic Courtès wrote on 20 Dec 2017 14:50
control message for bug #29675
(address . control@debbugs.gnu.org)
871sjpwlsg.fsf@gnu.org
tags 29675 notabug
close 29675
?