Mailinglist Archive: opensuse-factory (710 mails)

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Re: [opensuse-factory] filesystem query
  • From: Greg Freemyer <greg.freemyer@xxxxxxxxx>
  • Date: Thu, 2 Jun 2011 16:22:52 -0400
  • Message-id: <BANLkTi=mQ0PCM7+g6KwNGaLEwE3Aur1Szw@mail.gmail.com>
On Thu, Jun 2, 2011 at 4:00 PM, jdd <jdd@xxxxxxxxx> wrote:
Le 02/06/2011 21:27, Carlos E. R. a écrit :

Which means run fsck on all opened filesystems.

shouldn't. I usually see only a journal control

jdd

Remember meta-data journaling is fairly common.

Data journaling much less so.

Data journaling will be more robust, so if robustness is your issue,
give it a shot.

I don't know what filesystems offer data journaling, but ext3
definitely does. From the main page in the ext3 section:

==============
data={journal|ordered|writeback}
Specifies the journalling mode for file data.
Metadata is always journaled. To use modes other than ordered on the
root filesystem,
pass the mode to the kernel as boot parameter, e.g.
rootflags=data=journal.

journal
All data is committed into the journal prior to
being written into the main filesystem.

ordered
This is the default mode. All data is forced
directly out to the main file system prior to its metadata being
committed to the
journal.

writeback
Data ordering is not preserved - data may be
written into the main filesystem after its metadata has been committed
to the jour‐
nal. This is rumoured to be the
highest-throughput option. It guarantees internal filesystem
integrity, however it can allow
old data to appear in files after a crash and
journal recovery.
================

writeback is the least robust. Data can be written in any order and
conceivably sit in cache for extended periods. 5+ years ago, I think
this was the normal behavior for most mainstream filesystems.

ext3 now defaults to data=ordered (Remember the journals are flushed
on every mount, so it is easy to switch from one mode to another.)

I don't know if "data=journal" is any safer than "data=ordered" or not.

Hope this helps
Greg
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