Preallocation| control

(1) Would like allocate 512GB Lun (with preallocation of 150GB) to ESX-Server & Physical-Windows server. Will they see 512GB or 150GB size of disk on hosts? If they don't see it as 150GB then whats the advantage having preallocation?

Saurabh: dynamox has already answered that you would see 512 GB on the host, the advantage of preallocating a LUN is to avoid "write miss" penatly. When host writes to non preallocated tdev, tdev tries to allocate the track on the pool (which is equivalent to a write miss).  Also, preallocating gives you the liberty of blocking the space for your mission critical applications.

(2)  I have thin pool of 20TB; where my client is asking to 10TB to Preallocate and remaning without preallocation? Can i control preallocation upto 10TB at pool level? example--after allocation 1TBx10 luns with FULL preallocation; pool should not allow to create more preallocation on that pool.

Saurabh: Can you control preallocation to 10 TB at pool level? No, you cant. preallocation is done at tdev level. You do have an option at pool level (max subscription%) but it is for diff purpose.

regards,

Saurabh