On Aug 12, 0:55, Jim Davis wrote:
Subject: Disk space arithmetic I'm curious about accounting for the disk space on our filer, which has 19 "4gb" data disks.
Naively multiplying 19 disks * 4000 mb/disk * 1024 kb/mb gives 77824000 kb.
Now subtract 10% for the FFS-ish reserve space; that leaves 70041600 kb.
df on the filer shows 69682640 kb for / and /.snapshot combined. That leaves 358960 kb -- what did I overlook? Inode space? -- End of excerpt from Jim Davis
Disk manufacturers use metric megabytes...
19disks x 4 x 10 ^ 9Bytes/disk = 7.6 x10 ^ 10 = 76000000KBytes
Which shaves some off the difference. Having said that, most disks are actually 4.x GBytes, so you'll probably see the full 4GBytes useable.
I didn't think there was any FFSishness left in the WAFL - though WAFL metadata evidently requires a fair bit of space, especially if well used.
Have you already deducted the Parity and Hot Spares space?
19disks - 1 Parity - 1 HotSpare = 17 disks for user-data.
17disk x 4 x 10 ^ 9Bytes/disk = 68000000KBytes. Which looks very close to your figure from df...