here is one way .
This needs a bit of outage .
Assumption : fs01 is the filesystem that has been extended beyond limit say it was 10GB and now became 100GB which was not intended and used up space is 9GB
fs01 is mounted on /fs01 and shared as "fs01"
1. Create a required small size filesystem fs01 = 10GB
2. unmount the fs01 and mount it as ro as we do not want any changes during the copy.
3. mount the new filesystem fs02 as /fs02
4. use the ndmptool in the /nas/tools/ndmptool
5. use the copy filesystem functionality in the ndmptool and copy the
contents from fs01 to fs02
6. once the copy is finished unmount /fs02 and /fs01
7. mount the new fs02 as /fs01 ( reuse of the old mountpoint)
8. mount the fs01 as /fs01_temp
9. verify the access and data
10. once you are satisfied rename the old filesystem fs01 to fs01_delete
11. rename the newfilesystem fs02 as fs01 ( now you have the old shape of the fs01 with 10GB)
12 once you are happy with everything you can unmount the fs01_delete permanently and delete to reclaim space.
Make sure you disable the autoextend on the new filesystem so that it does not happen again .
or enforce quota for users .
The above procedure is same as .
backing up the filesystem using ndmp,
creating a new filesystem and restoring instead we use simple procedure without involving the DMA .