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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?
Thanks.
cincystorage
467 Posts
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February 26th, 2014 08:00
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.
chirswilson
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February 26th, 2014 13:00
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