[Nottingham] EXT4 no journal

[Martin]

Sergiusz Pawlowicz wrote:
> On Tue, Oct 13, 2009 at 10:00, Rory Holland
> <modestforagenius at googlemail.com> wrote:
>> I have a netbook wth an SSD, and have heard that running a journaled
>> filesystem can severely impact the lifetime (and performance for this
>> one!) of the drive.

The opinion from Theodore Ts'o is that a journal is no problem for an 
SSD. The additional writes are not significant.

See:

http://thunk.org/tytso/blog/2009/03/01/ssds-journaling-and-noatimerelatime/


>> However, I know ext4 brings many performance improvements over ext2,
>> so I would like to know if there's a way to disable the journal on an
>> ext4 partition. Google isn't much help, as there's lots of conflicting
>> information.

Google use that feature and are the driving force for it's use. They do 
all their data replication at the /application/ level. 'Extras' for 
filesystem security/integrity are just a slowdown for them.


>> I think there's a way using a livecd and the "tune2fs" tool.

Check out the man page:

-O ^has_journal

but specify all the other ext4 features that you want. See what you get! 
Let us know.


> i am not sure if these patches are incorporated to mainstream kernel:
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0390131ba84fd3f726f9e24fc4553828125700bb
> 
> but probably you can have a look at them.

Good find. That's long enough ago and with positive enough comments that 
it may well be in present kernels.

So... How do you check what is mainstream or not?


Cheers,
Martin

-- 
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Martin Lomas
martin at ml1.co.uk
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