I think most any Netapp admin has been in this situation: you set
aside a chunk of disk space for your snapshot reserve. After a week
goes by, you see that the reserve is at 150% of allocation. You
manually delete some snapshots until it falls back under 100%, and
adjust the snap schedule. A few months go by, new applications are
rolled in and old ones retire. Snapshot usage has also increased, but
you are at a loss to pinpoint the exact cause of the higher data
turnover rate.
What do people do to shed more light on this kind of situation?
I'd love to be able to conclude "It is the files in /vol/vol0/myapp/data
that are chewing up the most snapshot space" or "It is the write
activity coming from NFS client myhost1 that is causing the most block
turnover". I think I asked this question about five years ago and did
not discover an adequate solution back then. I'm hoping someone might
be able to share their expertise on this problem now. ;-)