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 Post subject: Re: Adding more disks to a CPG that is 95% full
PostPosted: Mon Jul 20, 2020 6:19 pm 

Joined: Fri Jul 17, 2020 11:34 am
Posts: 7
Here is part of the error that I think why tuning is not solving our problem. Idk if the CPG must be recreated or edited?

"NOTE: A CPG with customized LD characteristics can be limited to using a specified subset of total available space. That subset can reach these thresholds of percent full even when other physical space is still available."

appreciate your reply.


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 Post subject: Re: Adding more disks to a CPG that is 95% full
PostPosted: Mon Jul 20, 2020 7:45 pm 

Joined: Tue Mar 29, 2016 9:32 pm
Posts: 124
fiazshah wrote:
Here is part of the error that I think why tuning is not solving our problem. Idk if the CPG must be recreated or edited?

"NOTE: A CPG with customized LD characteristics can be limited to using a specified subset of total available space. That subset can reach these thresholds of percent full even when other physical space is still available."

appreciate your reply.


You're thinking as though the 3PAR is a traditional array with RAID sets you add disks too, it's not.
A CPG is NOT a container, it does not actually contain any gigabytes at all, it is a template.

When you create a volume you are telling it to create a volume using the shape described in the CPG template (RAID-5, across chunklets spanning 7 disks for example), the array will then create a logical device (or two or three or four ...) for your volume to sit across ... that logical device in turn is made up of chunklets spread across pretty much all the disks of the type defined in the CPG template.

Code:
3par-1 cli% showcpg
                        ----Volumes----- --Usage-- --------------(MiB)---------------
Id Name           Warn%  VVs TPVVs TDVVs  Usr  Snp      Base     Snp   Free     Total
 1 SSD_R1_VVol        -    1     1     0    1    1       512     512  39936     40960
 3 SSD_R5             -   94    94     0   94   94  41702656   48128  17152  41767936
 4 SSD_R5_Reclaim     -    0     0     0    0    0         0       0      0         0
 0 SSD_R5_VVol        - 3353  2651     0 3353 2256  63405440 1338112  26496  64770048
 2 SSD_R6_VVol        -    1     1     0    1    1       512     512  35840     36864
-------------------------------------------------------------------------------------
 5 total                                 3449 2352 105109120 1387264 119424 106615808


Above shows "capacity" info on CPGs here ... see the "Free" numbers ... that is not the number of free MiBs on the array or the CPG, that is the free space on logical devices created using the CPG template ... if it gets too low (16GiB I think on my array) the array just creates extras using the free chunklets on disks.


In regards to "capacity" of a CPG, all it shows is the total capacity of all logical devices/volumes using that CPGs template, and you can confgiure the CPG warn you or block the create of new LDs if it exceeds certain limits

Here is output from a test array here :

Code:
3par-1 cli% showcpg -alert
                        --------------Data--------------
                        -(MiB)-- -Setting(MiB)-   Alerts
Id Name           Warn%    Total     Warn Limit W% W L F
 1 SSD_R1_VVol        -     1024        -     -  - - - -
 3 SSD_R5             - 41750784        -     -  - - - -
 4 SSD_R5_Reclaim     -        0        -     -  - - - -
 0 SSD_R5_VVol        - 64743552 41943040     -  - Y - -
 2 SSD_R6_VVol        -     1024        -     -  - - - -


I've a warning limit on "SSD_R5_VVol" of 41TiB, but does nothing other than warn .. I could put a limit in there, which would then block the array from creating any more logical devices using that CPG template ... usually ends badly!!! :-)


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