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. ;-)