topic Re: Fractional reserve in Volumes without LUNs in ONTAP Discussions

Fractional reserve in Volumes without LUNs

KKU — Wed, 04 Jun 2025 14:53:39 GMT

Hello,

I'm a little bit confused.

I have some thin provisioned volumes without LUNs. They are published by NFS and CIFS.

We have provided the volumes with snapshot reserve 10% because we need snapshots.

We have no autodelete and no autosize enabled.

What is the difference in behaviour between fractional_reserve=0% and fractional_reserve=100% in these volumes?

Which value is recommended in these volumes?

Thanks,

Korinna

Re: Fractional reserve in Volumes without LUNs

sgrant — Tue, 04 Jul 2017 07:57:30 GMT

Hi Korinna, fractional reserve has no effect on any NAS volume, i.e. CIFS and NFS only. It only comes into effect for SAN volumes i.e. LUNs. So the setting can be either 0 or 100% it makes no difference, just leave it as default.

Please see https://kb.netapp.com/support/s/article/ka21A0000000gB5QAI/faq-how-is-space-utilization-managed-in-a-data-ontap-san-environment?language=en_US, which gives a little more detail.

Hope it helps.

Thanks,

Grant.

Re: Fractional reserve in Volumes without LUNs

KKU — Tue, 04 Jul 2017 08:07:56 GMT

Hi Grant,

yes, that is very helpfull.

I thougth so, but I wasn't sure.

Kind reagrds,

Korinna