Error message “cannot create incremental snapshot: No space left on device." setting up snapmirror

[storage_ergo]

Hi,

I get the message "“cannot create incremental snapshot: No space left on device." when trying to establish a snapmirror between two volumes on two systems. The source volume has about 200GB free and 87GB free in teh aggregate. I thought that this message would be cause if there were not enough space to create the baseline snapshot for snapmirror. Any ideas ? The systems are both on 7.3.1 and are both 3140's.

Thanks

[aborzenkov]

Any LUN on the volume in question?

[storage_ergo]

yes, there is a LUN there, it is consuming 90% of the volume space.

It is a 2.2 TB Volume, with a 2TB LUN in it. Fractional reserve is set to %100, does this need to be turned off ? will that impact anything on the volume ?

[adamfox]

You can't delete a LUN via cifs, espceically if it's online and mapped. 

You typically don't need space reservations on LUNs these days.  Most customers use volume autogrow and/or snap autodelete to handle space issues related to snapshots.  So if you're willing to do that, then you can turn off reservations and you'll get some space back.  If you wanted to destroy the LUN, I would do so via the lun commands and not via CIFS.

[adamfox]

Sorry about the CIFS stuff, got my threads confused.

But the stuff about autogrow and autodelete instead of space resevations still holds.

[storage_ergo]

Haha,

I knew something didn't sound right. Any how, we are not using snapshots on this particular volume so there would be no space to reclaim from that point. Also we don't have much space on the aggr left for vol autogrow either. THis seems to be one case where we can't use snapmirror for the lun. It is a 2TB lun in a 2.2TB volume with limited space available in the Aggregate.

[aborzenkov]

Fractional reserve is set to %100, does this need to be turned off ?

I would not put it this way. It may be turned off.

will that impact anything on the volume ?

In the worst case if you run out of free space during snapshot existence writing to your LUN will fail. It will likely upset host using this LUN. Turning fractional reserve off requires very good understanding how space in managed and permanent monitoring.

[radek_kubka]

Hi,

Fractional reserve is set to %100, does this need to be turned off ? will that impact anything on the volume ?

These two places may give you enough ammo to make a well-informed decision:

http://communities.netapp.com/groups/chris-kranz-hardware-pro/blog/2009/03/05/fractional-reservation--lun-overwrite

http://communities.netapp.com/thread/6108?tstart=0

Regards,

Radek

[DA_ORTEGA]

Hi,

I would like to know if changing the fractional reserve solves this problem? I am having the same issue with a 560G volume with 500G LUN. There's also not much space left in the aggregate. Also, there are no snapshots created for this volume so I'm not sure if frac-reserve will have an effect?

Thank you.

[scottgelb]

If you never are going to create snapshots, then you should run 0% fractional reserve... no use for it.