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Help Understanding CPG - Free Space - Volumes - AO
https://www.3parug.com/viewtopic.php?f=18&t=3107		 Page 1 of 1
Author:  walter_white [ Fri Feb 22, 2019 1:16 pm ]
Post subject:  Help Understanding CPG - Free Space - Volumes - AO
I'm trying to wrap my head around some very basic things in 3Par.. We have (8) 92GB SSD drives..

92GB * 8 = 736GB / 2 for RAID1 = 368GB..

However, my R1 CPG max size is 180GB (if I'm reading that correctly).. So 188GB is lost for "system" usage I'm guessing?

We only have 1 volume in a RAID1 CPG for this SSD..

Then it looks like 1 300GB volume was created and exported to 4 ESXi hosts. Of that 300GB, 165GB is used? But then in the VV screenshot it shows that 254.72 GB is used? WTF?

Then, to make matters even more confusing.. In VMWare, whoever set this up, added the Volume in VMWare as a 260GB datastore and VMWare saying 96GB is free..

Why create a 300GB volume when the max usable space is actually 180GB?
Why add it in VMWare as 260GB when it was exported as 300GB?

Thanks for the help..

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Author:  MammaGutt [ Fri Feb 22, 2019 3:20 pm ]
Post subject:  Re: Help Understanding CPG - Free Space - Volumes - AO
Long story short.

Default sparing reserves the capacity of 2 disks per 24 disk. That is most likely the system usage.
Quote:
showpd -c -p -devtype SSD

Should show that in CLI

VV is part of AO config. Most likely data is scattered
Quote:
showvvcpg

Will display who much data is stored per vv per cpg.

Vmware doesn’t clean up after itself (prior to VMFS6). You need to use unmap command in esxcli to reclaim deleted space.

I think that was all
Author:  walter_white [ Fri Feb 22, 2019 3:34 pm ]
Post subject:  Re: Help Understanding CPG - Free Space - Volumes - AO
MammaGutt wrote:
Long story short.

Default sparing reserves the capacity of 2 disks per 24 disk. That is most likely the system usage.
Quote:
showpd -c -p -devtype SSD

Should show that in CLI

MammaGutt wrote:
VV is part of AO config. Most likely data is scattered
Quote:
showvvcpg

Will display who much data is stored per vv per cpg.


AO is not enabled, and I don't believe ever has been.. There is an AO Config but there is no schedule so I don't believe it has ever run.. But is the below screen saying otherwise? So confused..

I get the system reserved space now.. But still confused on what is free, what is used, etc..

Thanks again

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Author:  MammaGutt [ Fri Feb 22, 2019 8:11 pm ]
Post subject:  Re: Help Understanding CPG - Free Space - Volumes - AO
Space...... simplified.

Physical disks are divided into chunklets (1GB)
Chunklets make up LDs.
LDs are generally created, controlled and owned by a CPG.
VVs are stored in CPGs.

So you probably have some free space on physical disk (RAW).
And some free space in CPGs (RAIDed)
And you might have some free space in VVs if they are doing unmap and is waiting to be reclaimed by 3PAR.

The «simple» way of knowing how much free space you have is to do compactcpg on all CPGs and look at the system wide free space (RAW)
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