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3PAR

hdzen
Occasional Contributor

3PAR


3PAR 7200

explain what is CPG set size and what does it affect how to calculate?
what is the default set size choose for Raid 5 Raid 6?

Thanks

5 REPLIES
Sheldon Smith
Honored Contributor

Re: 3PAR

The CPG set size is the total of data and parity chunkets in each RAIDset that contributes to the CPG's storage.
Read the HPE 3PAR StoreServ Storage Concepts Guide. You can find it and other 3PAR documentation at the Hewlett Packard Enterprise Information Library (http://www.hpe.com/info/storage/docs).


Note: While I work for Hewlett Packard Enterprise, all of my comments (whether noted or not), are my own and are not any official representation of the company.
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Venkatesh_SL
HPE Pro

Re: 3PAR

Dear Customer,

CPG isn't a container that has your volumes are in, it's not like a pool that you give disk space too, a CPG is just a template to say how you would like your volumes to be configured, so the space you see listed against the CPG is just the amount of space volumes are using that are using that CPGs template.

The CPG should automatically grow but it depends on which metric you are looking at for the free space. In some cases it can be that the CPG parameters are set in such a way that some of the space isn't by default available to that CPG e.g. you are enforcing cage level availability at the CPG and the CPG can't maintain that level of availability on the remaining free space in a given drive class.

If you do a 'cli% showspace -cpg *' that should list the CPG's, under EstFree column you'll see LDFree for the given CPG, divide that number by 1024 and it should provide the free space in GiB available to that CPG based on its current growth parameters. You can get the same from the CPG properties in the GUI.

The output of the following would be helpful for you to understand the space available:

"showsys -space"
"showcpg -space"
"showcpg -sdg"

Remember the CPG's in most cases will compete for the same space on the back end disks as such they grow based only on demand. Take a look at the concepts guide from page 43:

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04204225-6&lang=en-us&cc=us&docLocale=en_US


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vibeesh1
HPE Pro

Re: 3PAR

Hello Customer

The Number of chunkets on a given RIAD Set is called setsize.

Ifor Example, RAID 5 with 3+1  will have set size of 4 means 3 data and 1 parity.

Likewise for any of the RAID combinations. 

Thanks!
Vibeesh V

 

Wassim_SV
HPE Pro

Re: 3PAR

hello,

Find here the different combination of RAIDSet used for Raid 5 and RAID 6 for software version 3.3.1

–RAID 5 from 3 (2D+1P) to 9 (8D+1P)

–RAID 6 at  6 (4D+2P), 8 (6D+2P), 10 (8D+2P), 12 (10D+2P) or 16 (14D+2P)

–RAID 5 uses a set size (SSZ) of 4 (3D+1P) by default

I am an HPE Employee
Haitao_Zhang
HPE Pro

Re: 3PAR

Hello Customer,

Set Size – The number of chunklets in a Raid Set.   Logical drives are organized in rows of RAID sets. The set size is the number of sets within a row and serves a different purpose depending upon the RAID technology type: 

  • Examples (Note: these are not all the Raid Geometries and hence set sizes supported):

Raid 1 (1 + 1) has a set size of 2, one data chunklet and one copy chunklet

Raid 5 (3 + 1) has a set size of 4, three data chunklets and one parity chunklet*

Raid 6 (6 + 2) has a set size of 8, six data chunklets and two parity chunklets*

3PAR Support Specialist