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04-07-2017 03:41 AM
This might be very basic question. I need to understand sizings I see in 3PAR Management Console. I got a HPE 3PAR 7200 and 32 nos. of 1.2 SAS HDDs installed. Single CPG is created with disk selection as 'All Disks of type FC', which apparently selected all 32 disks. My questions are;
- When I view Physical Disks, I see all disks showing 'Total Capacity' as 1116GB. What is remaining GBs used for in each disk?
- Single CPG I mentioned above is created with default settings. Which are RAID Type: RAID5; Set Size: 3 data, 1 parity. What would be the usable space for this CPG considering all 32 disks are selected for this CPG?
- I got Virtual Volumes in following sizes, which sums up 24,580GB. I do see that in VVs tab under selected CPG. But how do I know if there any more VVs I can create or not? If yes, what size? (considering all 5 thinly provisioned VVs should be allowed to go until 90%)
- 5 nos. of 4096GB VVs - Thin provisioned
- 2 nos. of 1500GB VVs - Thick provisioned
- 2 nos. of 500GB VVs - Thick provisioned
- Under selected CPG summary sheet, I see estimated free space. What exactly does it mean? Does it mean actual free space without considering whole thinly provisioned spaces?
Sorry if I didn't clear my questions. Please do ask if any more information is required to answer questions.
Solved! Go to Solution.
04-07-2017 05:05 AM - edited 04-07-2017 06:23 AM
Re: Understanding sizing in HPE 3PAR Management Console
I think I got answer to my first question. Reading this article and then doing calculation based on info on the site, the actual space in single 1.2TB HDD comes down to 1117.5GB.
04-07-2017 06:47 AMSolution
Physical Disks: We have Spare chunklets (around 2.2 TiB), and we also need chunkets for the "admin" and ".srdata" system volumes. And formatting. And the difference between human (base 10) and computer (base 2). From a manufacturer's point of view, a 500GB drive has 500*1000*1000*1000 = 500,000,000,000 bytes. From a computer's point of view, 500G(i)B is actually 500*1024*1024*1024 = 536,870,912,000 bytes. A computer would 'see' that 500GB drive as being 465.66GiB.
RAID Type: RAID5; Set Size: 3 data, 1 parity 32 1.2 SAS HDDs should provide around 24.3 TiB.
Search the Internet for "why a hard drive has less than I thought". Also "GiB" (gibibyte): https://en.wikipedia.org/wiki/Gibibyte
The estimated free space on the CPG summary shows all free space if it were to be used by the CPG. A fully-provisioned 1000 GB volume will reduce the estimated free space by 1000 GB. A newly created thin 1000 GB volume will reduce the estimated free space by 1 to 2 GB. As data is written to a thin volume and it grows, the estimated free space decreases by the space used. After you write 100 GB to our thin volume, the CPG's estimated free space would still include the 900 GB not yet used by the volume.
Hope this helps clear things up.
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