In order to expand a VMAX Thin Pool we must first create the additional Data Devices (TDATs) on the underlying physical Disk Group. This example outlines how to calculate and create those TDAT devices and then expand the Thin Pool with the newly created TDATs.
A Disk Group that consisted of 64 X 600GB disk drives has been increased to 128 X 600GB Drives. EMC will be required to create and apply an upgrade BIN in order to expand the existing DG to 128 Disks, once this has been completed we can then proceed with the TDAT configuration.
After gathering the details with respect to the existing Hyper and TDAT sizes, then we can do a quick calculation in order to determine the count and size of the TDATs required (In this case the configuration is a simple replica of the existing configuration).
Calculating the Hyper Size
If we take the scenario above where a 64 Drive DG has been doubled to 128 Drives, with each of the first 64 drives in the DG having 8 Hypers per disk in a RAID 5 (3+1) configuration.
Listing the existing TDATs within Disk Group 1:
symdev list -disk_group 1 -datadev
Calculating the number of TDATs Required
From the image above you can gather that for each set of 4 Drives (Raid5 3+1) we require a total of 8 x TDATs.
8 Hypers * 64 Disks
=512/4 (R5 3+1)
Creating the New TDATs
Creating the new 128 x TDATs required on the newly added 64 Disks:
symconfigure –sid xxx –cmd “create dev count=128, config=Raid-5, data_member_count=3, attribute=datadev, emulation=FBA, size=206130 mb, disk_group=1;” Preview -nop
symconfigure –sid xxx –cmd “create dev count=128, config=Raid-5, data_member_count=3, attribute=datadev, emulation=FBA, size=206130 mb, disk_group=1;” Commit -nop
New TDAT Range Returned = 1177:11F6
List the new TDAT range created:
symdev list -datadev -disk_group 1 -nonpooled
Adding the new TDATs to the Thin Pool
Adding and enabling the new TDATs to the existing pool and thus essentially doubling the capacity of the Pool:
symconfigure -sid xxx -cmd “add dev 1177:11F6 to pool ‘Pool-Name’ type=thin, member_state=enable;” Preview -nop
symconfigure -sid xxx -cmd “add dev 1177:11F6 to pool ‘Pool-Name’ type=thin, member_state=enable;” Commit -nop
Rebalance the Pool
This command will rebalance the allocated extents in the Thin Pool nondisruptively across all of the enabled data devices in the pool. Automated pool rebalancing should be run whenever new data devices are added to a pool.
symconfigure -sid xxx -cmd “start balancing on pool ‘Pool-Name’ type=thin;” commit -nop
Check on the rebalancing progress:
symcfg -sid xxx -pool ‘Pool-Name’ verify -poolState -balancing
Display a detailed report of the expanded Pool
symcfg show -pool ‘Pool-Name’ -thin -detail -all -mb | more
The pool now consists of 256 TDATs (or 1024 Hypers!)