Data ONTAP Discussions

Pros and cons of having one LUN per volume?

When setting up LUNs for use with Vmware, what are the pros and cons of having each LUN in its own volume, please?




Re: Pros and cons of having one LUN per volume?

snapshots happen at the volume level so if you have multiple LUNs in a volume they all get snapped at the same time, whether they are all consistent or not.

Pro's of one lun/volume


1:  only have to quiesce the one lun when you want to take a snapshot

2:  can use snaprestore to restore the volume quickly. (potential performance hit with single file snaprestore)

Cons of one lun/volume


1:  more complicated setup

2:  volume count limitation

thats all i can think of for now.

Re: Pros and cons of having one LUN per volume?


Additional Pros:

1. Since you can prioritize I/O on a per volume basis with FlexShare (a.k.a. priority command) it is perhaps an advantage not to mix more than one LUN per volume unless they are the same "class" of I/O.

2. Related to other snapshot operations:  snapmirror operations to secondary storage can be differentiated a bit more on a per-lun basis. Moving luns to different aggregates can be one on a per-lun basis

Often enough, these things are just a matter of flexibility versus complexity.  As long as you aren't going to need hundreds of volumes (depending on the unit you have), one lun per volume is probably not a bad thing.  Read up on the Best Practices for setting up storage for vmware.  It can be a lot different than you think if you have used other storage systems.  Strategies like joining/concatting lots of small luns is pretty pointless on a NetApp.

Good luck.

Re: Pros and cons of having one LUN per volume?

De-duplication happens at the volume level, so if you have multiple luns with similar data like vm's you will save more space having them on one volume.