Re-capturing space

Re-capturing space

[Jason J. W. Williams]

Hello,
I'm looking at NILFS as a possible alternative to BTRFS for our move
off of ZFS. Looking at the description of how NILFS works, it seems
like it's one big log. New records go on the front. My question is how
does space eventually get recaptured when you delete files? Does the
log get rewritten/compacted regularly?

-J
--
To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Re-capturing space

[Ryusuke Konishi]

Hi,
On Wed, 10 Nov 2010 12:10:25 -0700, "Jason J. W. Williams" wrote:
> Hello,
> I'm looking at NILFS as a possible alternative to BTRFS for our move
> off of ZFS. Looking at the description of how NILFS works, it seems
> like it's one big log. New records go on the front. My question is how
> does space eventually get recaptured when you delete files? Does the
> log get rewritten/compacted regularly?
> 
> -J

Yes, a garbage collector daemon does that.  It copies "live" blocks to
the tail from the head of the log, and then frees some obsolete
segments from the log head.

Try "lssu" command to see how it works.

By default, the garbage collector (nilfs_clearned) will start when the
amount of free space falls below 10% of the disk space.

You can change it by modifying /etc/nilfs_cleanered.conf.

Regards,
Ryusuke Konishi
--
To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Re-capturing space

[Jason J. W. Williams]

Ryusuke,

Thank you very much for you answer! Does anyone run MySQL on NILFS or
is the random nature of database access poorly suited to good
performance on NILFS?

-J

On Wed, Nov 10, 2010 at 6:03 PM, Ryusuke Konishi <ryusuke-sG5X7nlA6pw@public.gmane.org> wrote:
> Hi,
> On Wed, 10 Nov 2010 12:10:25 -0700, "Jason J. W. Williams" wrote:
>> Hello,
>> I'm looking at NILFS as a possible alternative to BTRFS for our move
>> off of ZFS. Looking at the description of how NILFS works, it seems
>> like it's one big log. New records go on the front. My question is how
>> does space eventually get recaptured when you delete files? Does the
>> log get rewritten/compacted regularly?
>>
>> -J
>
> Yes, a garbage collector daemon does that.  It copies "live" blocks to
> the tail from the head of the log, and then frees some obsolete
> segments from the log head.
>
> Try "lssu" command to see how it works.
>
> By default, the garbage collector (nilfs_clearned) will start when the
> amount of free space falls below 10% of the disk space.
>
> You can change it by modifying /etc/nilfs_cleanered.conf.
>
> Regards,
> Ryusuke Konishi
>
--
To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html