topic Does maximum vol size for device include WAFL reserve? in ONTAP Discussions

Does maximum vol size for device include WAFL reserve?

WSANDERSATFLEXERA — Thu, 05 Jun 2025 05:35:57 GMT

Does maximum vol size for device include WAFL reserve or something nonobvious like that? Looks like the usable max vol size for 8.1.4 on a 3240 is actually quite a bit less than 50T as claimed in HW Universe:

> vol size vol4

vol size: Flexible volume 'vol4' has size 48318381160k.

> vol size vol4 +1m
vol size: Request to grow volume 'vol4' failed because the resulting volume size is greater than the maximum size.

That's only about 44T in 1024x1024x1024 units. We recently upgraded OnTAP from 8.0.2 to 8.1.4 to get a bigger aggregate size, but 8.1.4 upgrade only got me an additional 1TB max volume size. We were able to grow the aggregate to 48TB, so there is plenty of space in the aggregate. There are about 20 qtrees on the volume, but quota is off for the volume. SIs is on for the system, but not configured for this volume.

Snap reserve for this volume is 0 and nosnap is ON:

> vol options vol4
nosnap=on, nosnapdir=off, minra=off, no_atime_update=off, nvfail=off,
ignore_inconsistent=off, snapmirrored=off, create_ucode=on,
convert_ucode=on, maxdirsize=73400, schedsnapname=ordinal,
fs_size_fixed=off, guarantee=volume, svo_enable=off, svo_checksum=off,
svo_allow_rman=off, svo_reject_errors=off, no_i2p=off,
fractional_reserve=100, extent=off, try_first=volume_grow,
read_realloc=off, snapshot_clone_dependency=off, dlog_hole_reserve=off,
nbu_archival_snap=off

chesdfiler1a> vol status vol4
         Volume State           Status            Options
           vol4 online          raid_dp, flex     nosnap=on, create_ucode=on, convert_ucode=on
                                64-bit
                         Volume UUID: 4f3ec690-9acb-11e0-95ee-00a09816961c
                Containing aggregate: 'aggr2'

> aggr show_space aggr2

Aggregate 'aggr2'

Total space WAFL reserve Snap reserve Usable space BSR NVLOG A-SIS Smtape

57279822336KB 5727982232KB 0KB 51551840104KB 0KB 0KB 0KB

Space allocated to volumes in the aggregate

Volume Allocated Used Guarantee

vol4 48586816616KB 47413626408KB volume

Aggregate Allocated Used Avail

Total space 48586816616KB 47413626408KB 2961725708KB

Snap reserve 0KB 0KB 0KB

WAFL reserve 5727982232KB 400065692KB 5327916540KB

Re: Does maximum vol size for device include WAFL reserve?

JGPSHNTAP — Wed, 14 May 2014 18:03:12 GMT

Its easier if you look at the commands in the right context

df -Vh

df -Ah

can we see both those outputs

Re: Does maximum vol size for device include WAFL reserve?

WSANDERSATFLEXERA — Wed, 14 May 2014 18:12:41 GMT

> df -Vh vol4
Filesystem               total       used      avail capacity Mounted on
/vol/vol4/                44TB       44TB     1013GB      98% /vol/vol4/
/vol/vol4/.snapshot        0GB       21GB        0GB     ---% /vol/vol4/.snapshot
> df -Ah
Aggregate                total       used      avail capacity
aggr2                     48TB       45TB     2824GB      94%
aggr2/.snapshot            0TB        0TB        0TB     ---%

Re: Does maximum vol size for device include WAFL reserve?

JGPSHNTAP — Wed, 14 May 2014 18:24:08 GMT

hmm.. Not sure..

Re: Does maximum vol size for device include WAFL reserve?

billshaffer — Thu, 15 May 2014 19:46:49 GMT

The max volume size includes the 1% aggregate overhead and 10% volume overhead, or at least it did in 7.3. I worked out a spreadsheet once in order to determine the optimum backend lun size for a V-Series needed to maximize the volume usable space, and had to take both figures into account. I also had to take into account the checksum overhead - though I hear that, with native NetApp disk, that has gone away.

Bill

Re: Does maximum vol size for device include WAFL reserve?

WSANDERSATFLEXERA — Mon, 19 May 2014 16:24:11 GMT

There is some fine print. At the bottom of each hardware universe page"

3	The maximum usable aggregate capacity is roughly 90% of the values shown in the "Aggregate Size 32 bit(TB)" rows.

4	The maximum usable aggregate capacity is roughly 90% of the values shown in the "Aggregate Size 64 bit(TB)" rows.

5	The maximum usable FlexVol capacity is roughly 90% of the values shown in the "Flex Volume Size 32 bit(TB)" rows.

6	The maximum usable FlexVol capacity is roughly 90% of the values shown in the "Flex Volume Size 64 bit(TB)" rows.

This is misleading and inaccurate. I have created volumes that fill up 100% of the space of an aggregate (as sown by df -A), and volumes fill up to 100% of "usable space" all the time. Perhaps the fine print means "maximum size" instead of "maximum usable capacity"? In which case 88% for volumes is a more reasonable figure.