3Par 101 – Part 3 – Virtual Volumes and Vlun’s

In this series so far we have looked at 3Par’s approach to RAID and  CPG’s, now we get onto the stage where we can provision some storage to hosts by using virtual volumes and vluns!


Virtual volumes (VV’s) are HP’s terminology for what would most commonly be called a LUN, a LUN which has been presented or exported to a host is called a VLUN. Virtual volumes draw their space from CPG’s and come in two varieties Fully Provisioned Virtual Volumes (FPVV) and Thin Provisioned VV (TPVV). A FPVV uses all the allocated space upfront, so if a 100GB VV is created straight away 100GB of space will be used from the CPG. With a TPVV only the space that is demanded is used, so if a 100GB VV is created and only 50GB of that space is used only 50GB of space will be demanded from the CPG. A thin provisioning licence is required to use TPVV and assuming this is in place TPVV are the default type of VV created.


Creating a VV – GUI

Enough theory let’s get on and create a VV, first in the GUI:

1     In the management pane select Provisioning and then from the common actions pane select Create Virtual Volume


2 Next you will see a welcome screen which has a lot of useful info on creating VV’s, if you do not want to see this again click the skip this step tick box and click next


3 The basic information you will need to complete when creating a VV is highlighted in the screenshot below.   Thin provisioned will be selected by default, enter the name and size and then the CPG you want the VV to sit in. Remember the CPG you choose will determine the performance and availability level of the volume. The copy CPG will only be needed if you use snapshots



4 The screenshot below shows what you will see if you tick the advanced options checkbox. Generally you can leave all this to deafult and will not need to select advanced options



5 The final screen shows a summary of the sections you have made, if you are happy just click finish here



Creating a Vlun – GUI

Next we need to export (provision) the virtual volume to the host

1 In the management pane select Provisioning and then from the common actions pane select Export Volume


2 Next you will see a welcome screen which has a lot of useful info on creating VLUN’s, if you do not want to see this again click the skip this step tick box and click next


3 On the left hand side of the screen you need to select the name of the volume to export, on the right hand side you need to choose the host to export to. By ticking auto for export with LUN values it will automatically choose the LUN ID for you. When your happy with your selection click next


4 The final screen shows a summary of the sections you have made, if you are happy just click finish here


Creating a VV – CLI

createvv -tpvv -pol zero_detect NL_R6 VirtualVolume2 100G

Lets break down the CLI options a little

  • createvv – core command
  • -tpvv make thin provisioned volume
  • -pol zero_detect  scan for zeros on incoming writes
  • CPG name – in my case NL_R6
  • VV name – in my case VirtualVolume2
  • Size of volume – in my case 100GB


Creating a Vlun – CLI

createvlun VirtualVolume2 auto host1

  • createvlun – core command
  • VV name – in my case VirtualVolume2
  • Lun ID – auto in this case
  • Hostname – host1

If you have missed it, check out parts One and Two of this series.


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





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14 thoughts on “3Par 101 – Part 3 – Virtual Volumes and Vlun’s

  1. Dear, Thanks for your great and simple article
    i have a question about the availability of the whole 3par system
    how many physical disks can 3par bear their failure in the same time without loosing or affecting the data ?
    for older arrays like EVA , we lost some data due to failure of many disks in the same time which RAID could not rebuild the data
    i know that the “spare” concept here is virtualized not a physical spare “using spare chunklets”
    but what is the maximum number of simultaneous failed physical disks the 3PAR would loose data if it goes beyond that ?

    1. Hi welcome to the blog.

      The simple answer is it depends. First of all it will depend on the RAID level you have chosen, which disks fail and the sparing level you have set for you system. You can see what setting you have for sparring by running showsys -param form the CLI and looking for SparingAlgorithm.

      Any CPG is made up from logical disks. As we know from my post logical disks are chunklets arrange as rows of a RAID set. So if for example your CPG has a setting of RAID 5 3+1, your CPG will be built from many RAID 5 3+1 sets. Any RAID 5 set can tolerate a single disk failure, so how many disks can fail will depend on which RAID set the disk fails in. For example if you have a disk failure, and then another failure but the second failure is from a different RAID set then no data is lost. However if you have two failures from the same RAID set you will have data loss.

      This is assuming that system hadn’t completed rebuilding the data to spare chunklets. If the system completes sparing the counter is effectively reset. In summary like any storage system its best not to second guess it and get any failed disk replaced straight away.

      1. Hi,

        regarding to the spare chunklets, is it possible that 3par run out of spare chunklets ?
        does 3par able to rebuild spare chunklets from or to different RAID level ?

        1. Hi a number of chunklets are dedicated as spares when the system is first setup. If spares are then required the system first looks for local spare chunklets, then local free chunklets. It will then look for remote spare chunklets and finally remote free chunklets. So as you can see not only spare but free chunklets can be used and so as long as there is spare disk space the system will not run out. Local chunklets means the logical disk they sit on is owned by the same node which owned the failed chunklet.

        1. Each logical disk has a preferred owner i.e. a preferred node. If the spare chunklets are part of a logical disk that has the same preferred owner they are local. If they have a different owner they are remote.

  2. Hey 3PAR Dude! Loving the blog, now that I’m on KT for an account on which I’ll have to manage 3PAR. Just a quick one, on an existing Volume, is increasing capacity (Via GUI) as simple as hitting Edit and changing the Volume’s Size from there?

  3. Question: Is this correct? In creating a 1 tb lun: The steps are 1. create cpg 2. create virtual volume – link this to cpg and server; check export after creation and when finished everything looks great. This is sitting on a Red Hat 6.8 server. Next question: On the server, would one have to mount it in the system after the creation in 3par? What if after creation the server does not list it in the file system?

    1. Almost, when you create a volume you must choose which CPG to create it in, hence it is already linked to the CPG. Then you can export it to a sever. Once you have exported it you should just see it. Use showvlun to make sure everything looks OK and check your zoning.

  4. Hi 3PAR Dude, This blog is very useful Thank you for that. I have question Pl clarify. I have request to create 30+ VVol’s and map it to Cluster (2 windows). Is this step is correct in order ? 1) Create host sets 2) Create Hosts (2 here) 3) Add those 2 hosts to Host sets 4) Create VVol Set 5) Create Vvols 6) Add Vvols to VV Set 7) Map VVset to Host sets..

    if the above steps correct, how the lun id selection would be in order, the lun id order based on VVol creation priority (like if we have 30 luns created the the first created luns will have the ID of 0) ?

  5. Hi,

    Suppose there is a host connected to node 2 and node 3. For a 80 GB lun suppose LDs are equeally distributed between to node0, node1,node2 and node3 by 28GB/node(21gb data+7gb parity). How the host will use other LDs from node0 and node1 because host is connected to node 2 and node 3 only? Please explain

  6. We have 2 3par 7450s in our environment. We get virtually no dedupe.95% of our virtual volumes are TDVVs. The dedupe datastores consume roughly 40TB of storage on each array. Since we get no tangible space savings in regards to dedupe. Is it safe to say that we have 80TB of wasted capacity(40TB on each array used for the dedupe datastores)?

    1. Hi Stan thanks for the question. If you are not getting a good dedupe ratio like you say there is little value in having the volumes as a TDVV. It may however be worth waiting until 3.3.1 comes out as it has a re-write of the deupe code. After upgrade to 3PAR OS 3.3.1 you will need to create a new CPG and then move the volumes using DO to the new CPG to take advantage of the updated dedupe. I covered the enhanced dedupe here https://d8tadude.com/2017/02/21/3par-dedupe-compression/.

      Reach out to me on LinkedIn if you need to discuss further https://uk.linkedin.com/in/richardarnold2

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