Flash Cache

 
mdan_06
Visitor

Flash Cache

How do i expand the cache capacity of the 3Par using flash cache.

Please let me know how it can be achieved.

Thanks

6 REPLIES 6
sbhat09
HPE Pro

Re: Flash Cache

Hello @mdan_06,

Controller cache of 3PAR is fixed. For 8200/8400, it is 64GB per node pair and 8440/8450 it is 192GB per node pair. You can't expand the controller cache.

Flash cache is an additional, lower-level cache that you can create by reserving some portion of flash/SSD drives. Make sure you have sufficient free space in SSD drives. If it is a 4 node or 8 node system, there must be SSD drives (with free space) available in connected cages of all node pairs. Free space available must be more than the amount of flash cache you want to create.

Then you can create the flash cache using the command 'createflashcache <size>'. You can do it from SSMC as well.

Regards,
Srinivas Bhat


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mdan_06
Visitor

Re: Flash Cache

Thank you.

So, do you recommend Flash cache? 

Pro's and con's if any.. before i enable it.

Thanks in advance.

sbhat09
HPE Pro

Re: Flash Cache

Hello @mdan_06,

I certainly recommend flashcache for 10x faster disk IOps, especially data writes. Though your volumes are on FC/NL CPGs, original data writes will happen on SSDs. Later th the data moves to the disks where they actually belong.
Pros: You will get SSD write performance for all volumes in the system.
Cons: As much flashcache you reserve, that much SSD space will not be available as usable space.

There are no other important impacts or differences with the usage of flashcache.

Regards,
Srinivas Bhat

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sbhat09
HPE Pro

Re: Flash Cache

@mdan_06, additionally, I thought the below information will be handy for you:

The command to create flashcache is create -> createflashcache <size>[g|G|t|T]
If you don't mention the unit [g|G|t|T], system will assume it as MiB.
Example, the command to create 128GiB of flashcache may be:
createflashcache 128g or createflashcache 131072

The size of the flashcache must be a multiple of 16384MiB (or 16GiB).
Minimum size is 64GiB. The maximum size of the flash cache is based on the node types, ranging from 768GiB up to 12288GiB (12TiB).

You can create flashcache from SSMC GUI as well. Option will be under Main menu >> Optimization >> flashcache

Regards,
Srinivas Bhat

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Note: All of my comments are my own and are not any official representation of HPE.


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sbhat09
HPE Pro

Re: Flash Cache

Hello @mdan_06,

Was that explanation helpful to you?

Regards,
Srinivas Bhat


I am an HPE Employee

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mdan_06
Visitor

Re: Flash Cache

Hello Srinivas,

Yes. Thank you.