Any hyper limit for VMAX 10,20 & 40k

Question

hi VMAX gurus,

is there any Hyper limit for each disk in VMAX new series.

Recently we had a technical session for with EMC.As per the discussion,

New VMAX Series with Engunity 5876 works slightly different with VMAX with engunity 5875

While initializing the Array , the will add all the disks(with resepect to type) to one virtual pool where they will format all the disk drives to TDAT's and create one big pool with some specific raid configurations in backend.

Here are my Questions

Q1> so if we want to create any thick device we need to mention preallocate size to all is that true/not

Q2> If the above is the case then is there any hyper limit for these arrays (they said no hyper limit with engunity 5876 ) it that true

Q3> since we are creating such a big pool will it have any impact on CACHE

Can any one give clarification for my doubts.I was unable to ask these questions in the session.

Quincy561 · Accepted Answer

As far as I know, the only VMAX arrays that have pre-configured pools are the 10K arrays.  These arrays do not support thick devices.  All other VMAX arrays can have thick or thin or a mixture of both.

Quincy561 · Answer

I think the statement you saw refers to the 10K platform, which has pools preconfigured. They don't have to be kept as one large pool.

The number of devices in a given pool does not impact cache useage, the total capacity is the largest factor in cache use.

Thick devices have no preallocation, because they are not thin :-)

There is a maximum number of 64k devices in any VMAX, but smaller sized VMAX may have a lower limit.

You should avoid creating a LOT of physical hypers on the disk as it can create overhead.

gowrisankar1 · Answer

hi Quincy,

Thanks for your valuable comments,

but, i still have doubt in Q1> since while loading the bin file to the array we are saying that we are creating one virtual pool where are the disks will be added to the virtual pool, so there is no way of creating the thick devices right, since we need to carve out luns from the pool itself.In this case if we need thick lun then we need to mention the preallocate size right.

Can you please clarify a bit more in this case.

sauravrohilla · Answer

hi Fedex,I believe you are mixing thick and thin LUNs. Preallocation is done in thin device, Thick devices do not require any preallocation as Quincy said.If in case you are required to create thick luns, you dont need to mention any preallocation size.Hope it clears the thing..regards,Saurabh

gowrisankar1 · Answer

hi Quincy, Yes we have purchased VMAX 10k & the same has been communicated by the EMC, do you any supporting documents for this. I am not able to find on powerlink

sauravrohilla · Answer

Quincy, one quick question. With thin GK feature in 76 code are we still recommending customer to stick with physical GKs in 10K or its FULL VP solution in case of 10K? regards,Saurabh

Quincy561 · Answer

I would assume this should be documented in the product guide.  Also the DATA devices that are created can be added to separate pools if you want. You can also delete the devices and create new ones, but they have to be TDATs and TDEVs as the 10K does not support standard thick devices with the exception of GKs.

gowrisankar1 · Answer

hi Quincy,

I have read the product guide for VMAX 10k , but they didn't mention about these, yes it wont support standard thick, but if we need thick device we need to mention the preallocation size to 100.

Regards,

Fedex

Quincy561 · Answer

To me a pre-allocated thin device is still a thin device.

gowrisankar1 · Answer

how, can you justify....

Quincy561 · Answer

When I say thin device, I mean a TDEV that uses TDAT devices.  A thick device is a regular device that does not use a thin pool.  A fully allocated TDEV could become less than 100% allocated if the user ran zero reclaim.  So that is what I mean by 'thin', that it is a TDEV.

gowrisankar1 · Answer

Thanks a lot Quincy

Symmetrix

Any hyper limit for VMAX 10,20 & 40k

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