I was looking at my 630 trying to figure out if it was safe to add another nightly snapshot. According to the Sys-Admin manual on page 10-13 it shows an example where a snap reserve is set to 20% and a 'snap list' shows only 10% utilization. The suggestion is to drop the reserve from 20% down to 12 or 15% assuming usage patterns remain constant.
Great, this make sense to me. However, when I look at my system I have:
bigdisk> snap reserve Current snapshot reserve is 10% or 18976480 k-bytes.
bigdisk> snap list working...................................................... %/used %/total date name ---------- ---------- ------------ -------- 0% ( 0%) 0% ( 0%) Feb 18 12:01 hourly.0 1% ( 0%) 0% ( 0%) Feb 18 08:01 hourly.1 2% ( 1%) 1% ( 0%) Feb 18 00:01 nightly.0 2% ( 1%) 1% ( 0%) Feb 17 20:01 hourly.2 3% ( 1%) 1% ( 0%) Feb 17 16:01 hourly.3 3% ( 1%) 1% ( 0%) Feb 17 12:01 hourly.4 5% ( 3%) 2% ( 1%) Feb 17 08:01 hourly.5 7% ( 4%) 3% ( 1%) Feb 17 00:01 nightly.1
So, so far it would indicate that my 10% reserve is probably a pretty good number for the current setup and if I want to add another nightly snapshot I should probably bump my reserve up a couple of percent to be safe.
However, then I do a df:
bigdisk> df Filesystem kbytes used avail capacity Mounted on / 170788336 71454936 99333400 42% / /.snapshot 18976480 5180276 13796204 27% /.snapshot
I was expecting to see 70% utilization on my .snapshot file system here. Why is it only 27%? From this output I can only conclude that I have a lot of room and I don't need to bump up my reserve.
I must have missed something along the way.
-Rasmus