Tdev size - total vs total allocated

Question

hello,

can someone please explain the differance between total GBs vs Total allocated GBs below ? because we are noticing lun size discrepancy on vm hosts.

Here 0154 tdev original size is 1923 .8but what is 1806.3 ?

Also do the host see 1923.8gb or 1806.3 ?

$ symcfg -sid xxx list -tdev -gb -thin -pool xxxxx

Symmetrix ID: xxxx

Enabled Capacity (GBs) : xxx

Bound Capacity (GBs) : xxx

S Y M M E T R I X T H I N D E V I C E S

------------------------------------------------------------------------------

Total Total Compressed

Bound Flgs Total Allocated Written Size/Ratio

Sym Pool Name EMPT GBs GBs (%) GBs (%) GBs (%)

---- ------------ ---- ---------- ---------- --- ---------- --- ---------- ---

0154 xxxxxx FX.B 1923.8 1806.3 94 1699.7 88 1806.3 0

Appreciate any help.

thanks,

Raj

PedalHarder · Accepted Answer

The host will see the total amount. Since this is a thin environment, the total capacity of the device does not need to be allocated in the thin pool. That is one of the major benefits of thin technology.

When the device is created, you have the option to determine how much storage is actually allocated in the pool. this can be anywhere from 0 to 100% and this will be reflected in the Allocated GB.

Even if the allocated GB was 100%, by running a RECLAIM on the device (to free all the allocated but unused capacity), the Allocated amount will be reduced.

The x flag suggests that this device has allocations across multiple pools. Since you are only looking at one pool in your command, this may another reason why the numbers are not working for you. Try symcfg -sid xx list -tdev -gb -detail.

This will give multiple lines of output for each device that has allocations across multiple pools.

Fenglin1 · Answer

Jason is correct. Host will see 1923.8gb, but 1806.3gb is used in the Array. The differential between two numbers can be sync via RECLAIM operation by using SYCLI:

symconfigure -cmd "start reclaim on tdev 0154;" commit -sid xxx

The verify command can be useful when scripting operations, which will check to ensure a given thin device has begun reclaiming

symcfg verify -tdev -reclaiming -dev 0154 -sid xxx

Before perform operation, following white paper can be refer through EMC online support

EMC Symmetrix VMAX Virtual Provisioning Space Reclamation and Application Considerations:

https://support.emc.com/docu32785_Symmetrix_VMAX_Virtual_Provisioning_Space_Reclamation_and_Application_Considerations.pdf?language=en_US

VMAX

Tdev size - total vs total allocated

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