Hi David,
 
as far as i can see, everything is as expected.
When you have fractional_reserve set to 100 (%), as soon as you create snapshots on that volume, ontap will reserve 100% of the Luns size within the volume, to gurantee writes to complete successfully.
 
The maths show:
 
820GB * 0,8 (for snap reserve) = 656 GB
 
320GB Lun * 2 (for fractional reserve) = 640 GB
 
P = 640 / (656*100) = 97,56 %
 
Think ontap is doing some rounding, so 98% is correct.
 
Regards
 
Jochen


From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of David.Ashton@rullion.co.uk
Sent: Thursday, September 04, 2008 12:04 PM
To: toasters@mathworks.com
Subject: Noob...


Hi, please excuse my noobness, I've recently inherited a Netapp system or 3, I'm fairly new to SANs in general and netapp in particular. This isnt my full time gig (storage), its one thing amongst the 2 thousand other things I'm working on today, but I allocate a fair amount of time to figuring this stuff out.

I'm struggling with something I'm sure all netapp storage people go through, I've read the manuals, I've played around for about 6 months on the filers and I cant answer this.

I have a FAS3020. I have a volume, lets call it vol_bond. Its 820GB, 20% snap reserve. It contains one lun, which is 320GB. The space guarantee is volume, and fractional reserve is 100.

Currently, there are 5 snapshots, totalling 8GB. It is snap mirrored to another filer.  Snapshots are created nightly, there are no problems with that. At weekends, after various backup activity, these grow to about 80GB, but we only keep 5 and they're deleted.

Its all up and running, everythings fine.

Except for the filer status which reports: /vol/vol_bond is full (using or reserving 98% of space and 0% of inodes, using 49% of reserve) and the df -r output is

/vol/vol_bondv8/     687865856  670681368   17184488  335194536  /vol/vol_bondv8/
/vol/vol_bondv8/.snapshot  171966464   14140040  157826424          0  /vol/vol_bondv8/.snapshot

What am I missing? I thought I had this thing nailed but obviously not.

Dave Ashton

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