zfs discuss - Sep 2010 - When Zpool has no space left and no snapshots

Dear ZFS Discussion,

I ran out of space, consequently could not rm or truncate files. (It
make sense because it''s a copy-on-write and any transaction needs to
be written to disk. It worked out really well - all I had to do is
destroy some snapshots.)

If there are no snapshots to destroy, how to prepare for a situation
when a ZFS pool looses it''s last free byte?

Alex

Preemptively use quotas?


On 9/22/10 7:25 PM, "Aleksandr Levchuk" <alevchuk at gmail.com>
wrote:
> Dear ZFS Discussion,
> 
> I ran out of space, consequently could not rm or truncate files. (It
> make sense because it''s a copy-on-write and any transaction needs
to
> be written to disk. It worked out really well - all I had to do is
> destroy some snapshots.)
> 
> If there are no snapshots to destroy, how to prepare for a situation
> when a ZFS pool looses it''s last free byte?
> 
> Alex
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

--
Scott Meilicke | Enterprise Systems Administrator | Crane Aerospace &
Electronics | +1 425-743-8153 | M: +1 206-406-2670


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On Wed, September 22, 2010 21:25, Aleksandr Levchuk wrote:
> I ran out of space, consequently could not rm or truncate files. (It
> make sense because it''s a copy-on-write and any transaction needs
to
> be written to disk. It worked out really well - all I had to do is
> destroy some snapshots.)
>
> If there are no snapshots to destroy, how to prepare for a situation
> when a ZFS pool looses it''s last free byte?
Add some more space somewhere around 90%, or earlier :-).

If you do get stuck,  you can add another vdev when full, too. Just
remember that you''re stuck with whatever you add "forever",
since there''s
no way to remove a vdev from a pool.
-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

You can truncate a file:

Echo "" > bigfile

That will free up space without the ''rm''

-----Original Message-----
From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss-bounces at
opensolaris.org] On Behalf Of David Dyer-Bennet
Sent: Wednesday, September 29, 2010 12:59 PM
To: zfs-discuss at opensolaris.org
Subject: Re: [zfs-discuss] When Zpool has no space left and no snapshots


On Wed, September 22, 2010 21:25, Aleksandr Levchuk wrote:
> I ran out of space, consequently could not rm or truncate files. (It
> make sense because it''s a copy-on-write and any transaction needs
to
> be written to disk. It worked out really well - all I had to do is
> destroy some snapshots.)
>
> If there are no snapshots to destroy, how to prepare for a situation
> when a ZFS pool looses it''s last free byte?
Add some more space somewhere around 90%, or earlier :-).

If you do get stuck,  you can add another vdev when full, too. Just
remember that you''re stuck with whatever you add "forever",
since there''s
no way to remove a vdev from a pool.
-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

_______________________________________________
zfs-discuss mailing list
zfs-discuss at opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

On Wed, September 29, 2010 15:17, Matt Cowger wrote:
> You can truncate a file:
>
> Echo "" > bigfile
>
> That will free up space without the ''rm''
Copy-on-write; the new version gets written to the disk before the old
version is released, it doesn''t just overwrite.  AND, if it''s
in any
snapshots, the old version doesn''t get released.

-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info