DMX 3 Cache question

Question

I have a DMX 3 with 196,608 MB of usable cache. If I look at the output below it shows 1,879,748 available cache slots. if you do the math it looks like I'm only using 117,484 MB of cache. Is this formula correct?

(1879748 * 64)/1024

If it is, where did 70 GB of my cache go?

Cache Size (Mirrored) : 196608 (MB)
# of Available Cache Slots : 1879748
# of PermaCache Slots In Use : 433
Max # of System Write Pending Slots : 1505266
Max # of DA Write Pending Slots : 752633
Max # of Device Write Pending Slots : 75260

Quincy561 · Accepted Answer

You can get a ballpark figure of the meta data consumption by assuming 300MB of cache needed for every 1TB of protected capacity, including VDEVs, SAV devs, etc. (for DMX3 and DMX4)

Based on what you provided, "I have 195TB configured and 54 TB vdevs" adads That would be 195+54= 249TB * 300MB = 74700MB / 1024 = 72GB of meta data.

HankDorsett · Answer

How about this question.How does cache get configured? Bin file? System auto configs based on available cache?

Quincy561 · Answer

I would be interested to know how much usable capacity is configured in your system. Include cache only devices such as Virtual SNAP devices, and SAV pool devices. There is meta data used from your cache, and you can estimate how much based on the capacity configured.

HankDorsett · Answer

I have 195TB configured and 54 TB vdevs.

Symmetrix

DMX 3 Cache question

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