2012-02-17 12:46 AM
Good morning everyone,
I'm having a weird issue with my FAS2020 running OnTap 7.3.6.
My volume 1 is 1,35TB.
System is reporting than this volume has only 221GB available (1116 MB used).
The thing is, I only have 2 lun created on this volume (200 + 500 GB). Snapshots are using 40 GB. Total : ~750GB used.
So, I was wondering where are the missing ~400GB ?
Am I missing something?
Thanks for your help,
2012-02-17 01:06 AM
fs1101> df -h
Filesystem total used avail capacity Mounted on
/vol/vol0/ 8755MB 640MB 8114MB 7% /vol/vol0/
/vol/vol0/.snapshot 460MB 152MB 308MB 33% /vol/vol0/.snapshot
/vol/vol1/ 1382GB 1161GB 220GB 84% /vol/vol1/
/vol/vol1/.snapshot 153GB 43GB 110GB 28% /vol/vol1/.snapshot
fs1101> df -Ah
Aggregate total used avail capacity
aggr1 2093GB 1555GB 538GB 74%
aggr1/.snapshot 110GB 87GB 22GB 79%
fs1101> aggr show_space -h
Total space WAFL reserve Snap reserve Usable space BSR NVLOG A-SIS
2449GB 244GB 110GB 2093GB 0KB 0KB
Space allocated to volumes in the aggregate
Volume Allocated Used Guarantee
vol0 10GB 887MB volume
vol1 1544GB 520GB volume
Aggregate Allocated Used Avail
Total space 1555GB 521GB 538GB
Snap reserve 110GB 87GB 22GB
WAFL reserve 244GB 24GB 220GB
fs1101> aggr status
Aggr State Status Options
aggr1 online raid4, aggr root
fs1101> vol status
Volume State Status Options
vol0 online raid4, flex root, create_ucode=on
vol1 online raid4, flex no_atime_update=on,
2012-02-18 01:17 AM
This is vol1.
Output of df -rh :
fs1101> df -rh
Filesystem total used avail reserved Mounted on
/vol/vol0/ 8755MB 640MB 8114MB 0MB /vol/vol0/
/vol/vol0/.snapshot 460MB 153MB 307MB 0MB /vol/vol0/.snapshot
/vol/vol1/ 1536GB 1217GB 318GB 463GB /vol/vol1/
/vol/vol1/.snapshot 0GB 51GB 0GB 0GB /vol/vol1/.snapshot
Yesterday, I changed reserved snapshot space to 0%. But no luck.
2012-02-18 01:41 AM
463GB is reserved for LUN overwrites due to fractional_reserve volume setting. This is done to protect you from out-of-space condition on LUNs. Please, read TR-3483 (or TR-3965 that includes 8.1) that describes in details how NetApp manages space in case of LUN.
2012-02-18 04:34 AM
You may run out of space on the volume, so that host write to LUN fails. As hosts normally do not expect hard disks to run out of space, they do not handle it gracefully.
Default settings on NetApp ensure, that there is always space for new write to LUN, so it behaves exactly as conventional disk.
2012-02-18 05:03 AM
What I don't understand is, why would a host require to write beyond my lun configured limit?
I created a 500GB lun on vol1 which is used by XenServer. XenServer know it has 500 GB available and not more.
In what case(s) would the "space reserve" be used?