* [linux-lvm] lvmtrim
@ 2011-10-19 12:48 Yann Droneaud
2011-10-19 12:56 ` Alasdair G Kergon
0 siblings, 1 reply; 6+ messages in thread
From: Yann Droneaud @ 2011-10-19 12:48 UTC (permalink / raw)
To: linux-lvm
Hi,
Is there any tool for LVM like fstrim(8) (which would likely be called
"lvmtrim") ?
http://thread.gmane.org/gmane.linux.utilities.util-linux-ng/3695
This tool would discard currently unused PE of an active VG like
fstrim(8) is doing on ext4,btrfs,xfs blocks (depending on filesystem
support).
Regards.
--
Yann Droneaud
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] lvmtrim
2011-10-19 12:48 [linux-lvm] lvmtrim Yann Droneaud
@ 2011-10-19 12:56 ` Alasdair G Kergon
2011-10-19 13:07 ` Alasdair G Kergon
2011-10-19 13:26 ` Yann Droneaud
0 siblings, 2 replies; 6+ messages in thread
From: Alasdair G Kergon @ 2011-10-19 12:56 UTC (permalink / raw)
To: Yann Droneaud; +Cc: linux-lvm
On Wed, Oct 19, 2011 at 02:48:20PM +0200, Yann Droneaud wrote:
> Is there any tool for LVM like fstrim(8) (which would likely be called
> "lvmtrim") ?
vgtrim
> This tool would discard currently unused PE of an active VG like
> fstrim(8) is doing on ext4,btrfs,xfs blocks (depending on filesystem
> support).
Sounds a reasonable idea to me, although I question how the PEs that
would benefit from it would have got into that state in the first place,
given that lvreduce already has trim support if you had
devices/issue_discards = 1 in your lvm.conf.
Alasdair
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] lvmtrim
2011-10-19 12:56 ` Alasdair G Kergon
@ 2011-10-19 13:07 ` Alasdair G Kergon
2011-10-19 13:16 ` Alasdair G Kergon
2011-10-19 13:26 ` Yann Droneaud
1 sibling, 1 reply; 6+ messages in thread
From: Alasdair G Kergon @ 2011-10-19 13:07 UTC (permalink / raw)
To: Yann Droneaud; +Cc: linux-lvm
On Wed, Oct 19, 2011 at 01:56:54PM +0100, Alasdair G Kergon wrote:
> vgtrim
Suggested spec if someone wants to implement this:
1) factor out the discard code from release_pv_segment so it can be shared
and used on existing segments too;
2) Add vgtrim (+man page) which takes VG-style arguments, uses
process_each_pv_in_vg which uses process_each_segment_in_pv which checks if
segment is free and if so calls the code from (1) to issue a discard on it.
Alasdair
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] lvmtrim
2011-10-19 13:07 ` Alasdair G Kergon
@ 2011-10-19 13:16 ` Alasdair G Kergon
0 siblings, 0 replies; 6+ messages in thread
From: Alasdair G Kergon @ 2011-10-19 13:16 UTC (permalink / raw)
To: Yann Droneaud; +Cc: linux-lvm
On Wed, Oct 19, 2011 at 02:07:23PM +0100, Alasdair G Kergon wrote:
> 2) Add vgtrim (+man page) which takes VG-style arguments, uses
> process_each_pv_in_vg which uses process_each_segment_in_pv which checks if
> segment is free and if so calls the code from (1) to issue a discard on it.
Adding a new cmd involves:
create tools/vgtrim.c (e.g. use stripped down vgdisplay.c as template?)
Add to SOURCES in Makefile
Add section to commands.h (alphabetically)
Alasdair
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] lvmtrim
2011-10-19 12:56 ` Alasdair G Kergon
2011-10-19 13:07 ` Alasdair G Kergon
@ 2011-10-19 13:26 ` Yann Droneaud
2011-10-19 13:29 ` Alasdair G Kergon
1 sibling, 1 reply; 6+ messages in thread
From: Yann Droneaud @ 2011-10-19 13:26 UTC (permalink / raw)
To: LVM general discussion and development
Le mercredi 19 octobre 2011 à 13:56 +0100, Alasdair G Kergon a écrit :
> On Wed, Oct 19, 2011 at 02:48:20PM +0200, Yann Droneaud wrote:
> > Is there any tool for LVM like fstrim(8) (which would likely be called
> > "lvmtrim") ?
>
> vgtrim
>
> > This tool would discard currently unused PE of an active VG like
> > fstrim(8) is doing on ext4,btrfs,xfs blocks (depending on filesystem
> > support).
>
> Sounds a reasonable idea to me, although I question how the PEs that
> would benefit from it would have got into that state in the first place,
> given that lvreduce already has trim support if you had
> devices/issue_discards = 1 in your lvm.conf.
>
Perhaps when you forgot to discard/TRIM the whole SSD before re-using it
in an active VG.
Perhaps in the case you're migrating from an older version of the LVM2
tools ?
Or issue_discards was set to 0.
Regards.
--
Yann Droneaud
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] lvmtrim
2011-10-19 13:26 ` Yann Droneaud
@ 2011-10-19 13:29 ` Alasdair G Kergon
0 siblings, 0 replies; 6+ messages in thread
From: Alasdair G Kergon @ 2011-10-19 13:29 UTC (permalink / raw)
To: Yann Droneaud; +Cc: LVM general discussion and development
On Wed, Oct 19, 2011 at 03:26:15PM +0200, Yann Droneaud wrote:
> Perhaps when you forgot to discard/TRIM the whole SSD before re-using it
> in an active VG.
> Perhaps in the case you're migrating from an older version of the LVM2
> tools ?
> Or issue_discards was set to 0.
Indeed.
It's a simple tool to write, so I'm throwing it open to see if anyone wants
to write and contribute it
Alasdair
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-10-19 13:29 UTC | newest]
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2011-10-19 12:48 [linux-lvm] lvmtrim Yann Droneaud
2011-10-19 12:56 ` Alasdair G Kergon
2011-10-19 13:07 ` Alasdair G Kergon
2011-10-19 13:16 ` Alasdair G Kergon
2011-10-19 13:26 ` Yann Droneaud
2011-10-19 13:29 ` Alasdair G Kergon
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