Snapmirror source volume snapshot size

[cvoigt]

We have snapmirror up and running for 4 volumes on one of our filers, we do one snapmirror every night for each volume.  One of the volumes began failing it's nightly snapmirror the other day due to lack of disk space on the source volume (0% snapshot reserve).  When looking at the space usage of existing snapshots for the working volumes, I'm confused as to why the snapmirror transfer size is not the same as the snapshot stored on the source volume.  What dictates the size of snapshot stored on the source volume?  I know it should be the delta of the data on volume since the last snapshot, and this seems to be reflected in the snapmirror transfer size but not the source volume snapshot (which is always seems to be smaller).

[radek_kubka]

Hi and welcome to the Community!

Are you taking the snapshot only nightly, or more frequently? If the latter is true: SnapMirror will need to transfer all changes since the previous update, not just from the last snapshot.

Regards,
Radek

[cvoigt]

Thanks for the welcome, long time lurker.

We are taking only one snapshot nightly.

Here is one of the (source) volumes that is successfully being snapmirrored. (ONTAP Release 7.3.5.1P2)

Name:	vol3
Type:	Flexible	Root Volume?	-
FlexClone ?	-	Containing Aggregate:	aggr0
Status:	online,raid_dp
Used Capacity:	758 GB	Space Guarantee	volume
% Used:	74%	Language:	en_US
Total Capacity:	1 TB	Total Size:	1 TB
Number of Files:	363	Max Directory Size:	20.5 MB
Max Files:	31.9 m
SNAP Mirror?	-	SNAP Directory?	X
SNAP?	X	Resync SNAP Time:	60
SVO Enable?	-	SVO Checksum?	-
Allow SVO RMAN?	-	SVO Reject Errors?	-
Create Unicode?	X	Convert Unicode?	-
Minimal Read Ahead?	-	NV Fail?	-
Fractional Reserve :	100	Extent?	-
FS Size Fixed?	-	Update Access time?	X
I2P?	X	Ignore Inconsistent??	-