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How to use VIOS with Nvme disks to virtualize disks for IBM i

  • 1.  How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/02/24 11:50 AM

    Hi guys.
    I need to configure a partition IBM i with disks hosted by VIOS using MVMe disks. 
    I found a blog on this community called "NVMe device support in Virtual IO Server (VIOS)" posted 2020 by NINAD PALSULE, but he wrote only solution about AIX and Linux. 

    I couldn't find in the web any reference about this scenario with IBM i,  and  I need to do a similar configuration to the one described in the blog, but using the IBM i partition.
     
    Can anyone help with this question by providing some documentation or experience? 

    Thanks 

    Reinaldo



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    Reinaldo Santos
    Support Engineering
    AS Tecnologia e Serviços
    Sao Paulo
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    #PowerVM


  • 2.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 04:37 AM

    Hi,

    The solution will really be the same for IBMi.  Create LVs in the VIOs (I'm assuming dual VIOs) to use as VSCSI backing devices and present to the LPAR, mirror within the LPAR (IBMi level) across the VIOs for redundancy.

    Phill.



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    Phill Rowbottom
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  • 3.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 05/28/25 04:55 PM

    Hello, 

    In my case, I only have a card for one VIOS and an internal NVMe disks.
    Does this mean I should assign all resources to the VIOS and present them via SCSI to the IBMi ?
    I have done IBMi setups using NVMe but have not had to use VIOS.

    Thanks in advance



    ------------------------------
    Martha Orozco
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    Original Message


  • 4.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 05/29/25 02:28 AM
    Edited by Satid S 05/29/25 02:38 AM

    Dear Matha

    >>>> In my case, I only have a card for one VIOS and an internal NVMe disks. Does this mean I should assign all resources to the VIOS and present them via SCSI to the IBMi ? I have done IBMi setups using NVMe but have not had to use VIOS.<<<<<

    The question you asked was without contextual information.  Whether you use VIOS or IBM i to host virtual disk resources for client LPARs depends on contextual factors that you need to identify and use as the information base for your decision on whether to use VIOS or IBM i as the host.     

    One additional information about using IBM i to host virtual disk.  I used to encounter 2 cases where an IBM i LPAR hosted virtual disk (from NVMe) to another client IBM i LAPR (both in low-end Power servers) and the client IBM i LPAR saw quite bad disk response time (2-18 msec.) despite the fact that the host LPAR saw very consistently good disk response time (0.5 msec.at all times). I asked my customers to open service calls to IBM Support team but did not pursue the case, so I have no idea what caused the issue.  So. be careful when you use IBM i LPAR as a host for virtual disk resource to client LPAR.   



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    Satid S
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    Original Message


  • 5.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 05:48 AM

    Dear Reinaldo

    What you asked for has very little to do, if at all, with IBM i.   The basic action steps you take in VIOS in creating all vSCSI adapter and disk units from the NVM owned by VIOS are the same regardless of what OS run in the client LPAR of that VIOS.   When you create vSCSI server adapter in VIOS, be sure to note down its Adapter ID number that you assign to it - to be later associated with vSCSI client adapter you create in IBM i LPAR definition.   When you create the IBM i client LPAR definition, add vSCSI client adapter to it and specify the name of target VIOS host LPAR and its associated  vSCSI server adapter ID number you note down previously.  Then you put Load Source Unit tagging to the vSCSI client adapter of IBM i LPAR.   After you finish preparing your IBM i install image files, start IBM i LPAR and follow standard action steps for installing IBM i.  



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    Satid S
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  • 6.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 05:54 AM
      |   view attached

    For configuring and tagging vSCSI client adapter in IBM i client LPAR, look at page 33-36 and 48-49 of the attached presentation for an idea. Keep in mind the GUI look may be different.

     



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    Satid S
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    Attachment(s)

    pdf
    IBM i Hosting IBM i Step-by-Step-May2018.pdf   3.73 MB 1 version


  • 7.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 08:44 AM
    Edited by Reinaldo Santos 10/03/24 08:44 AM

    Hi Phill and Satid.

    I understood your answers. Thanks very much guys. 

    I had already done the configuration offering the NVMe disks directly to the IBM i, but never using the VIOS.

    My question comes up with the difference in disk formatting, which in VIOS is the same for AIX and Linux (512-byte sector). In the case of IBM i, it's different, 520-byte sectors.

    And since I have to deliver all the disks to VIOS, I had understood that they would inherit the VIOS formatting when I offered them to IBM i.

    Sorry for overthinking.

    Thanks Satid for the document, it will help a lot.


    ------------------------------
    Reinaldo Santos
    Support Engineering
    AS Tecnologia e Serviços
    Sao Paulo
    ------------------------------



  • 8.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 09:10 AM
      |   view attached

    Dear Relnaldo

    >>>> My question comes up with the difference in disk formatting, which in VIOS is the same for AIX and Linux (512-byte sector). In the case of IBM i, it's different, 520-byte sectors.

    And since I have to deliver all the disks to VIOS, I had understood that they would inherit the VIOS formatting when I offered them to IBM i.  Sorry for overthinking.   <<<<

    No worry here. As of IBM i 6.1, it was enhanced with the ability to handle disk units with 512-byte sector.  I attach a past article discussing this enhancement if you want to read some details. 



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    Satid S
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    Attachment(s)

    pdf
    HW-V6R1 512Byte Disk Sector Support.pdf   68 KB 1 version
    Original Message


  • 9.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 09:17 AM

    Hi Reinaldo,

    Unix systems can also access disks in character (raw/no filesystem) mode which is what is happening when using the LV as a backing device to a VSCSI disk.   From  my understanding a VSCSI device is a VSCSI device to the VIOs client, it doesn't matter what type of backing device is behind it, it presents the same to the client, it could be a SAN LUN, Logical Volume, Physical Volume - they all look the same to the client due to what is going on in the VIO/Hypervisor layer. 

    Disclaimer - I'm not an IBMi guy, but we do run IBMi on the same hardware as AIX & Linux where I work with full virtualisation.

    Phill.



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    Phill Rowbottom
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    Original Message


  • 10.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 08:50 AM

    Hi Reinaldo 

    Short hint: You need to use filebacked storage for that :) 

    Kind regards 



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    Jan Henrik Radl
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  • 11.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 08:50 AM

    Hi

    For that I use file backed storage locally on the vios server. 

    Kind regards 



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    Jan Henrik Radl
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  • 12.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 10/03/24 01:58 PM

    Thanks folks.

    The information you've given me is important for eliminating my doubts. I hope to have the environment described here available to configure in no more than 10 days and I'll post the results here.



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    Reinaldo Santos
    Support Engineering
    AS Tecnologia e Serviços
    Sao Paulo
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  • 13.  RE: How to use VIOS with Nvme disks to virtualize disks for IBM i

    Posted 01/16/25 10:19 AM

    I have tried this before in the past with non nvme disks and  didn t work very well with LVM, file backend disks was the best workaround i found. Let us know if with nvme and actual versions of PowerVM is different and moreover if performance is acceptable 



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    Hugo B
    Managing Director
    Sixe Ingeniería
    Madrid
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