Viewing Free Capacity in 3Par

How much free capacity has my 3PAR got?  This seems like a simple question but I see lots of questions about it. The SSMC has simplified viewing the 3PAR capacity information significantly so lets start there .

SSMC

Raw Capacity

When you open the 3 PAR SSMC you will see the dashboard view. In the dashboard you will see a number of widgets that will help you with your 3PAR capacity management, the widgets are as follows:

Total capacity – This shows you the total raw capacity. For clarity this raw capacity is just the sum of the capacity of all the disks in your system and takes no account of RAID levels, sparing etc.

Device Type Capacity – This again measures raw space but this view allows you to see it by device type i.e. the type of disk be that FC, NL or SSD

Allocated capacity – Another raw figure, this takes the total capacity allocated which means used and shows you what it is using up the space dividing it up by block, file and systemThe above widgets show the capacity for ALL systems connected to SSMC, to see the capacity information for a single system click on the widget in the dashboard. You can also drill down to the capacity for a single system by opening the main menu, and then choosing systems, then choosing the capacity view.

Useable Capacity

The capacity measures we have looked at so far have shown raw space available in different ways. Potentially the figure you will be most interested in will be how much space is actually available to be written to i.e. what is the useable space. For this we need to look at the CPG level

From the main menu choose Common Provisioning Groups. If you cannot see this option choose show more from the top right

In the left hand pane choose the CPG you are interested in checking the available space for. In the right hand window look at the Capacity Summary widget. When you look at this you will probably look at the free figure and see there is not much space left. Once you finish nearly having a heart attack thinking you are about to run out of space, let me reassure you that this figure is highly misleading. CPG’s grow on demand and this figure will always show a small amount of free space.

The figure you are really interested in is the Estimated maximum CPG size. This is the figure that shows the useable capacity available to the 3PAR. Be mindful that multiple CPG’s can consume space from the same set of physical disks, check out our CPG Overview if you need a refresher on this

Command Line

If you are a command line junkie you can get exactly the same stats from the CLI. To view get a similar view of disk capacity utilisation as in part 1 run

showsys – space

To view writeable capacity left on a CPG as in part 2 run the below, the figure you are interested in is LD free

showspace -cpg cpgname

     -------------------------(MB)--------------------------

 CPG -----EstFree----- ------Usr------ ---Snp---- ---Adm----

 Name RawFree   LDFree   Total   Used Total Used Total Used

R6 15954816 10636544 2051840 2048000     0   0     0   0

3PAR Management Console

Raw Space

If you still use the 3PAR management console read on. The first thing to understand is how much capacity has been consumed on the physical disks. This is simply as a percentage how full are the disks. The steps to find this are below

  • Open up your 3PAR Management Console
  • Select systems from the navigation pane
  • Highlight the name of your SAN in the management tree
  • In the management window choose the capacity tab.

It’s quite self-explanatory. The top of the windows shows the total for all the different types of disks in your system and then breaks this down by disk type below, this is then further broken down into allocated and free space. So for example the above screen shot shows the fast class disks are 88.51% full.

Next you want to know what’s gobbling up all that space. If you expand the disk class you are interested in you will see it then splits this into space used by the system v space used by volumes

capacity 2

You can keep drilling down further and further on an item. Like below, I’m looking at what proportion of the allocated space is taken up by the volume itself and how much is snapshot space. Have a play and you will get the idea.

Ok so now we know how much space is left on our physical disks but the key question is how much actual writeable space is left for critical stuff like the marketing department to store their pictures in. You can view this on a per CPG level.

Useable Space

This part deals with the question how much writeable space have I got left in the CPG.

  • Open up your 3Par Management Console
  • Select provisioning from the navigation pane
  • Then from the management tree highlight CPG’s
  • In the management pane on the top right highlight the name of the CPG you want to look at
  • Choose summary in the bottom management pane
  • The stat you are interested in is estimated free system space, shown in the bottom management pane

So the above screenshot shows that there is 10,387GiB of writeable space left on this CPG. Writeable space takes account of the amount of space consumed by raid parity, system space etc. and tells you how much space is actually available for volumes to grow into.

With the CPG space figures you need to be aware if you have other CPG’s on the same set of physical disks they will also be competing for the space. So for example in the above screenshot the 10,387GIB may not be for exclusive use by the CPG you are looking at. Also be aware that some CPG’s will consume space much faster than others, for example a raid 1 CPG will use up space much quicker than a raid 5 CPG.

 

Hopefully knowing these methods will allow you to manage the capacity of your 3PAR system more easily

To stay in touch with more 3PAR news and tips connect with me on LinkedIn and Twitter.

 

 

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15 thoughts on “Viewing Free Capacity in 3Par

  1. As a storage admin, I am a big fan of 3Pars. This said, I must confess that guessing free space is tricky as hell, specially on thin provisioned environments.

  2. Hi, great articles and easy to understand. I was hoping you may have information on the ‘CPG Growth Warning’ for AO? I am having a difficult time understanding if the CPG Growth warning should use the ‘CPG logical disk size’ or the ‘physical raw disk size’. The CPG size is much smaller to account for the RAID 6. Thank you in advance.

    1. Hi thanks for the feedback.

      As this alert relates to the CPG you would use the CPG space. Have a look what the total useable space is for the CPG and then set the warning as a proportion of this.

      1. Hi, thank you for your reply. The total usable space for the CPG is that the ‘Allocated Space’ value directly below the ‘CPG Growth Warning’ on the image of the CPG Details?
        Just wanted to confirm I am checking the correct value for ‘total CPG space’.

  3. Allocated capacity = includes usable space, snap space, admin space( raid protection)

    reserved space = includes spare chucklets?

    system space=?

    1. I assume you mean Virtual Volumes. This is because pre server 2012 when data was deleted it did not actively pass back the message to the SAN that data had been deleted. You needed to use utilities like sdelete to force the write of zeros.

  4. What happen if you do not run unmap or sdelete on LUN at host end and delete that LUN from 3par after unexporting that volume, will 3par be able to reclaim that space back to system?

    1. No need to run any kind of space reclaim command like sdelete. Once you delete the LUN space will be returned to the CPG. If you want to return the space to the whole system you would run a compactcpg after that

  5. Thanks for the article. This has been helpful. Since you correctly assumed I’d freak out about free space, I wanted to make sure I understood exactly.

    Here’s what I saw yesterday:
    Dashboard:
    – Total Capacity: Allocated 51TB, Free: 7.4TB, Total 58.5TB
    – Allocated Capacity: Block 47.7TB, System: 3.3TB, Total: 51TB
    CPG:
    Capacity Summary: Used 37.3TB, free 1.9TB, Allocated 39.2TB

    I then deleted multiple VMs, ran the unmap command on all of my VMware datastores and, after that was done, ran a compactCPG.

    Now, I see the following:
    Dashboard:
    – Total Capacity: Allocated 48.2TB, Free: 10.2TB, Total 58.5TB
    – Allocated Capacity: Block 45TB, System: 3.3TB, Total: 48.3TB
    CPG:
    Capacity Summary: Used 37.5TB, free 111GB, Allocated 37.6TB

    If I understand things correctly, because I ran unmap and then compacted my CPG, THAT is why my free space is frighteningly small. But, the important piece is that my total free capacity is 10.2TB so I really have 17% free space that my CPG can/will use to auto-grow.

    Is that correct? I can breathe and rest easy knowing I have 10.2TB of growth left on my CPG?

    1. Hi

      It sounds like you ran the correct process and allocated has gone done and free has gone up which is positive. The scary free 111GB is the amount of space left in the CPG before it auto grows again, nothing to worry about. The 10.2TB you now have free is raw capacity. For the useable capacity look at the Estimated maximum CPG size, in Capacity Summary

      Hope that helps

      Richard

  6. Hi,

    If I enter showvv -space, I get a big difference between reserved usersapce and Used user space. Volumes does not appear to release space to CPG over time. Is this something you have encountered?

    Regards

    Mats

    1. Hi Mats

      Yes, The 3PAR will only release free space back if the OS of the connected host instructs it to do so. This only happened natively starting with vSphere 6.5 and Server 2012. Prior to this you will need to run unmap and sdelete manually.

  7. Hi again,
    connected OS in question is VMware. Unmap has been run and this is what has generated a lot of free space in VV’s, but no space is beeign returned to CPG as far as I can tell. 3Par OS is 3.2.2 MU3.

    For Volumes in total
    Rsvd Used
    43810816 34268598

    This is system volumes included where dds volume differs ~ 4 TiB in rsvd / used

    Regards

    Mats

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