HP 3PAR 7200 SPACE CALCULATION

[Ceciliok]

Hello experts,
i have a 3par 7200 populated with 215 disks as broken below 
141 Disks are 546 Gbs (600GB)
75 Disks are 1,116 tbs (1.2TB)
i created a  1 CPG  with raid 6 (14 data disks t 2 parity)
however i have a task of explaining to the customer the space descripancy as they cannot allocate more space. 

both the disk types combained they would give atleast 160686 Gbs 
but the allocatable space given by the 3par console is only 53312 Gbs that means we are missing around 107374 Gbs. 

please help me understand this

[Satish04]

Hi Ceciliok,

In CPGs created with RAID 6, some disk space is reserved for parity and system overhead, which can cause the actual usable disk capacity to differ from the total raw disk capacity.
When you use RAID 6, you have two parity disks per set, reducing usable capacity compared to RAID 0. In order to protect data from disk failures, this overhead is necessary.
There is a reserve of space in the HPE 3PAR Storage system for metadata, system snapshots, and other administrative functions.
The HPE 3PAR Storage system divides storage into 1GB chunklets, which are smaller than physical disks. There may also be some overhead associated with this.
Thin provisioning can lead to the allocated space not reflecting the total capacity of the disks until the data is actually written to them.
Explain these factors to the customer and reassure them that the discrepancy is due to necessary system functions.

Hope this helps.!

Regards,
Satish

[Ceciliok]

Hello @Satish04 

Thank you for the submission. However on deeper analysis, i observed that am using an old 3PAR and so it wasnot giving acurate results when observing the CPG capacity and so i created more luns even when it was showing 99% the were created and i later observed that acurate results were observed from the disk themselves. 

so its actually the 3par console that was giving me false information.

Kind Regards

Cecilio Kisitu 

[Ramesh_Kumar_P]

We request you to log a case on HPE Support Center portal for further resolution using the link: https://support.hpe.com/hpesc/public/home/

Thank you!

[sbhat09]

Hello @Ceciliok,

Please share the CLI outputs for the below commands. Let me explain the space allocation:

showpd -c
showpd -i
showflashcache

Regards,
Srinivas Bhat

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