topic Re: 7-mode deduplication 100% in ONTAP Discussions

7-mode deduplication 100%

HenryUK — Wed, 04 Jun 2025 21:47:31 GMT

Hi All

i am working with a FAS2050 with 2.4TB on each controller

yesterday we started to enable dedup 1 volume at a time (excluding vol0)

vol2 went from 412GB @ 96% to 63% (400GB lun)

whihc was a great start

today vol3 went from 415GB 94% to 100% (251GB lun) instantly and says snapshot creation failed

what would be the reason for this? there are no snapshot copies visable from oncommand

any ideas

Re: 7-mode deduplication 100%

aborzenkov — Tue, 15 Mar 2016 11:04:43 GMT

De duplication creates snapshot internally. So it may happen. The first thing to check would be fractional reserve settings.

Re: 7-mode deduplication 100%

HenryUK — Tue, 15 Mar 2016 11:10:10 GMT

can yo give me some guidance on the commands?

Re: 7-mode deduplication 100%

HenryUK — Tue, 15 Mar 2016 11:12:19 GMT

i see there is an enable fractional reserver 100%

i am investigating that now i can just disable this yes?

Re: 7-mode deduplication 100%

aborzenkov — Tue, 15 Mar 2016 11:29:53 GMT

Fractional reserve ensures your LUNs won't suddenly get out of space. Make sure you understand implications before disabling it.

Re: 7-mode deduplication 100%

HenryUK — Tue, 15 Mar 2016 13:16:40 GMT

okay thank you - i have taken off the fractional reserver whilst i run the dedup as there is plenty of space and no backups are performed using storage snapshots

when the dedup has completed i will re-enable

Cheers