When upgrading a NetApp filer from a pre-7.3 release to 7.3, metadata is apparently moved from within the FlexVol into the containing aggregate. If your aggregate is tight on space – more than 96% full – NetApp requires that you complete extra verification steps to ensure that you can complete the upgrade. From the Data ONTAP® 7.3.1.1 Release Notes (NOW login required):

If you suspect that your system has almost used all of its free space, or if you use thin provisioning, you should check the amount of space in use by each aggregate. If any aggregate is 97 percent full or more, do not proceed with the upgrade until you have used the Upgrade Advisor or aggrSpaceCheck tools to determine your system capacity and plan your upgrade.

Upgrade Advisor is a great tool, and I heartily recommend you use it for your upgrade. However, it doesn’t give you a lot of visibility into what’s being checked for here. Lucky for us, NetApp offers an alternative tool: aggrSpaceCheck (NOW login required).

AggrSpaceCheck, as written, relies on you having rsh turned on for access to the filer – something that you probably locked down when you were still wearing acid-washed jeans. Assuming you don’t have rsh access, you’ll see an error like this when you attempt to run aggrSpaceCheck:

> perl aggrSpaceCheck.pl -filer toaster01

aggrSpaceCheck V1.0.0 Copyright (c) 2008 NetApp 

Could not retrieve Aggregate free space. Could not get any aggregates in this filer

The fix is easy, however, if you’re using SSH: Edit the aggrSpaceCheck.pl file, replacing “rsh” with “ssh” (you only need to actually edit it in the line where “$remCmd” is defined, but changing rsh to ssh elsewhere won’t hurt). You will be prompted for root’s SSH password repeatedly – once for each command run remotely on the filer:

> perl aggrSpaceCheck.pl -filer toaster01

aggrSpaceCheck V1.0.0 Copyright (c) 2008 NetApp 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 
root@toaster01's password: 

Aggregate aggr0 requires 54.18GB for volume metadata; 137.76GB is available.
Aggregate aggr0 has enough free space for you to upgrade to 
Data ONTAP 7.3 or later.

There’s a solution for this too, of course: Enable SSH key pair authentication from your management host to your filer – no more password prompts:

> perl aggrSpaceCheck.pl -filer toaster01

aggrSpaceCheck V1.0.0 Copyright (c) 2008 NetApp 

Aggregate aggr0 requires 54.18GB for volume metadata; 137.76GB is available.
Aggregate aggr0 has enough free space for you to upgrade to 
Data ONTAP 7.3 or later.