[systemd-devel] [PATCH] Set the NOCOW flag for the journal via tmpfiles

[Cameron Norman]

On Sun, Mar 29, 2015 at 12:43 PM, Goffredo Baroncelli
<kreijack at libero.it> wrote:
> Hi,
> did you find the time to give a look a these patches ? Do you have any suggestions ?
>

I do not know about anyone else, but this message was in my spam box.
The reason was: "It has a from address in libero.it but has failed
libero.it's required tests for authentication".

Best regards,
--
Cameron Norman

> On 2015-03-21 12:56, Goffredo Baroncelli wrote:
>>
>> Hi all,
>>
>> these patches set reverts the commit 11689d2 "journald: turn off COW for
>> journal files on btrfs" which enables *unconditionally* the NOCOW flag for the
>> journal files. The reason was that the performances of the journal file format
>> are very bad on btrfs, and decrease during the time. Disabling the COW
>> behavior, the perfomances increase.
>> Unfortunately disabling the COW behavior leads to disable the BTRFS checksums,
>> which in turn prevents BTRFS to rebuild a corrupted file in a RAID
>> filesystem [3].
>>
>> To avoid that I proposed a patch which introduces a configurable option to
>> disables the "turn off COW" behavior[1]. Lennart commented that instead he
>> prefer to set the NOCOW attribute via tmpfile.d snippets.
>>
>> A further patches set was proposed and accepted [2] to extend systemd-tmpfiles
>> to change the file attributes.
>>
>> This last patches set removes the "turn off COW" behavior (patch #1) and
>> introduces a new tmpfiles.d snippet which enable the NOCOW beahvior for the
>> journal files (patch #2). So a sysadmin can disable this setting overriding
>> this file configuration.
>>
>> BR
>> G.Baroncelli
>>
>>
>> [1] Re: [systemd-devel] [RFC][PATCH] Add option to enable COW for journal file
>> https://www.mail-archive.com/systemd-devel@lists.freedesktop.org/msg28724.html
>>
>> [2] https://www.mail-archive.com/systemd-devel@lists.freedesktop.org/msg29313.html
>>
>> [3] http://en.wikipedia.org/wiki/Btrfs#Checksum_tree_and_scrubbing
>>
>> --
>> gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
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