Where's my disk space hiding?

[chamor]

I'll admit I'm not overly experienced with the daily handling of 3Par arrays, not at all infact. However, I'm tasked of sizing the expansion of an existing system.

I've looked in various screens and exported several reports.

This system is an F400 3.1.1 with 96 600 GB FC drives and 16 1 TB SATA drives.

When I look at the combined "Allocated capacity" for the two CPGs using FC drives, I get a little less than 29.000 GiB.

If I report the TPVVs and sum up "RawReservedUserSpace" for the FC CPGs (and the very little RawReservedCopySpace", most copy space is on SATA drives) I get about 35.000 GiB.

Fair enough I guess, some space is used by spares and other overhead.

However, using "showspace" on the CLI, I get
Estimated RawFree (MB)
9.390.080

Do the math: 96x600 gives me 56.250 GiB Raw.

Take this minus the "Estimated RawFree" and I'm left with roughly 47.000 GiB used. I admit, doing the conversions to and from MB, GB, GiB etc makes a something lost in translation. And ok, I need some spares and stuff, but this is well over a 10 TB discrepancy?

What am I missing here? Incidently, the number for the SATA drives add up reasonably well doing the same math.

[Conrad]

Are you using TPVVs? If so, free space has to do with the growth value, not with how much is actually available.

[Richard Siemers]

So the raw free is exactly that... unallocated raw free space.

So by your math you calculated that to mean 47 TB used... however "used" is not the correct word, "Allocated" would be correct.

There is free space in the CPGs, and VVs that are "allocated".

So your CPG "Allocated" capacity of 29 TB = your TPVV's "RawReservedUserSpace" of 35 TB... raid over head cost displayed there. I am guessing based on those numbers you are using raid5 or 6 with a set size of 6?


The showspace command is important and does some math behind the scenes. For example, it can take into account your CPG configuration... so if your CPG is filtered to never use any FC disk in magazine position 1, then it will take that into account when calculating free space. Also, it takes into account your availability settings, such as cage safe or mag safe. As space is allocated to the CPGs, it has to maintain a set of rules that prevents raid-lets from sharing the same mag/shelf etc. the showspace command helps you navigate through that complex math.

That said, do your FC CPGs have any special settings or filters? or can both fully use ALL of the FC spindles?

[Richard Siemers]

P.S. The IMC gui may provide a better view.

Click on the Systems view, then your T800, then the capacity tab.