Saturday, May 11, 2013

Create, expand, destroy NetApp volumes

Volume:  A volume is a logical unit of storage, containing a file system image associated with administrative options. One can create up to 500 volumes on a single filer depending upon the model and ontap versions. I recommend to keep that number low.

Flexible volumes are independent entities carved on aggregates, which can be increased and decreased.

Size: Minimum of 20 MB to Maximum of 16 TB

'vol' suite allows us perform several operations mainly creating, expanding, offline, online, destroy, copy and many more. I am restricting this post only to explore few and also to set 'popular' options that I use when I create a volume.

Volume Creation:

Create a thin volume with name vol1 of size 500 GB on aggr1, 0% fractional reserve, with no snaps.

Step:1 Check for available space on aggregate

aggr -Ahx

step:2 Create volume with specified options

vol create vol1 -s none aggr1 500g

#set fractional reserve to 0%

vol options fractional_reserve 0

#There are several default options that will be applied when a volume is created depending on the ontap version, you can verify then as follows:

vol options vol1

Step:3 No snaps

snap sched vol1 000
snap reserve vol1 0
snap autodelete vol1 on

Step:4 Verify

vol status vol1

Expand Volume:

Expand the volume created above by another 600 GB

Step:1 Check for available space

aggr -Ahx

Step:2 Expand the volume by 600 GB

vol size vol1 +600g

After completion it show the new expanded size.

Offline and destroy Volume:

Take the above created volume offline and destroy it.

This operations needs to be done with extra consciousness, if you screw up-you are fired!

Step:1 Confirm there is no activity on the target volume from CLI or OCUM

stats show -e volume:vol1

#make sure you see all of the counters '0'

Step:2 Offline the volume

vol offline vol1

#confirm with your server admins that users are not complaining

Step:3 Destroy the volume

vol destroy vol1


Fractional Reserve: If you are wondering what fractional reserve is, lets take a scenario where you have a volume of size 600 GB with a lun of 500 GB and also say you have the snaps turned on.

If you are not monitoring the snaps and allowing them to grow beyond the limits, you will obviously be out of space on the volume which leads to bad things! So if you set the fractional reserve to 100% it will reserve another 600 GB space on the aggregate for eliminating the volume being offline when the snaps conquer the volume.

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