2 Bronze

How to decipher thin pool capacity/usage on VMAX

Hi all, I am working with a client who has a VMAX and I am trying to understand what some of these capacity numbers mean. The client told me that create thin devices but fully allocate them, but if that was the case I'm not sure I would see such a large difference between alloc % and subs %. What information can I gather from these #'s?

I'm also confused with the percentages from the SATA pool, how can the subscription for a pool be higher then the allocated?


vmax pools.jpg

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3 Cadmium

Re: How to decipher thin pool capacity/usage on VMAX

An easy way to think of subscription is how much space would be uses if every device was suddenly written to 100%.  Allocated is how much is actually consumed of the pool based on how much the host is actually using.  I'm guessing they don't really fully allocate each thin device. 

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2 Iron

Re: How to decipher thin pool capacity/usage on VMAX

It looks like FAST is enabled which would explain the subscription numbers, allocation may come from another pool, you want to look at the array allocation and subscription as a whole, not just pool by pool.   I find the command line gives a better view of what's going on.  

symcfg -sid xxx list -thin -pool -detail

Shows the same info as the screenshot but also gives an overall array subscription and allocation.

symcfg -sid xxx list -tdev -detail

Lists each device and it's allocations, drop the -detail if you just want the check the allocation percentage, this shows if they are really fully allocated

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