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Hyper-v storage

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  • Hi everyone,

    I am reading a lot about best practices for storage distribution regarding Hyper-V in order to get the best perfomance.

    I need to setup a host with 3 VM's for a client (35-to 50 user environment) and from what I read it seems that I need the following:

    1Drive for Host Operating System

    Guests:

    DC: 1 IDE Drive for OS, 1 scsi for Logs+Sysvol, 1 Scsi for Page file

    File Server: 1 IDE for OS, 1 Scsi for for page file

    RDS:(Session Based desktop deployment) 1 IDE for OS, 1 Scsi for Page File.

    In addition I will need a separate scsi drive for an old custom application and an additional scsi disk for General data.

    All of the above is a result of endless reading and I am wondering: A small environment needs 10 disks?? and what about Raid?

    Would it make any difference if I do Raid 10 with 4 drives (Host OS separate on RAid1) and put each VM on a different partition? Also create different partitions for data and applications and different partitions for page files?

    Thanks.

    mercoledì 25 settembre 2013 17:07

Tutte le risposte

  • Hi everyone,

    I am reading a lot about best practices for storage distribution regarding Hyper-V in order to get the best perfomance.

    I need to setup a host with 3 VM's for a client (35-to 50 user environment) and from what I read it seems that I need the following:

    1Drive for Host Operating System

    Guests:

    DC: 1 IDE Drive for OS, 1 scsi for Logs+Sysvol, 1 Scsi for Page file

    File Server: 1 IDE for OS, 1 Scsi for for page file

    RDS:(Session Based desktop deployment) 1 IDE for OS, 1 Scsi for Page File.

    In addition I will need a separate scsi drive for an old custom application and an additional scsi disk for General data.

    All of the above is a result of endless reading and I am wondering: A small environment needs 10 disks?? and what about Raid?

    Would it make any difference if I do Raid 10 with 4 drives (Host OS separate on RAid1) and put each VM on a different partition? Also create different partitions for data and applications and different partitions for page files?

    Thanks.

    1) Boot OS from a cheap SATA RAID1. I'd recommend to use WD RE because of a better URE rate. 

    2) Keep VMs on a RAID10. Calculate your typical VM IOPS load, multiple to safe factor 1.5 or 2, keep in mind RAID10 write penalty of a 1/2 (reads are just a sum of a spindle IOPS because RAID10 does wide striping) and you'll see how many spindles you need. Will you go for SAS or will you need only SATA (preferred because of the capacity).

    3) Get a decent DR plan as you have a single point of failure (your storage). Consider having virtual SAN if you want to run at least dual hypervisor hosts (that would be naturally better way to spread the load and provide good uptime). Many hosts and virtual SAN could be an overkill for your RTO/RPO and amount of the VMs. Maybe not... But VM backup is a must. Even with a free Hyper-V Replica (a bit ugly in terms of usage and does not support set of a production workloads with Exchange and SQL Server, could be a problem for you, pain to deal with non-Windows VMs but does pretty good job for a virtualized desktop Windows OS).

    4) You're done with a perfect virtualization setup :)


    StarWind iSCSI SAN & NAS

    mercoledì 25 settembre 2013 19:45
  • DC: 1 IDE Drive for OS, 1 scsi for Logs+Sysvol, 1 Scsi for Page file

    File Server: 1 IDE for OS, 1 Scsi for for page file

    RDS:(Session Based desktop deployment) 1 IDE for OS, 1 Scsi for Page File.

    With virtual machines, unless you are putting the various virtual disks on different spindles/controllers, you will not see much performance difference than when you place everything in a single virtual disk.  This is particularly true for the page file.  The page file is hardly accessed for a machine that has the proper amount of memory.  I generally set my page file to only about 2 GB and leave it on the system drive.  For the size system you are talking about, I see no benefit in trying to have multiple virtual hard drives as you have described.  For a file server, I could easily be convinced to have a separate drive for the files to be shared, but more for backup and recovery and management rather than performance.

    There is minimal performance difference between IDE and SCSI drives in Hyper-V VMs.  Under the covers, they use alot of the same code.

    So you could get by with about 6 virtual drives, but that is information carved out of whatever physical storage you present to Hyper-V.  That could be one large disk or files on a RAID volume.  Remember that a virtual hard drive is nothing more than a file.


    .:|:.:|:. tim

    mercoledì 25 settembre 2013 23:10
  • Thank you Tim for your reply.

    I think that there is a general confusion about virtual drives and physical drives. I was refering to physical drives wondering if that model would be better (one physical drive for each function) or if it would be ok to have raid1 for host os and Raid 10 for everything else. Also would it make any difference if I create multiple partitions on Raid 10 instead of placing everything in one big drive. Page file on separate drive so that it can be excluded from replication. Still not sure if I need a separate physical drive a separate vhdx on a Raid 10 or a separate partion that will have the vhdx.

    Could someone out there given the information I provided give me some specifics. How many drives typr of Raid etc.

    Thanks,

    Leo

    mercoledì 25 settembre 2013 23:59
  • Thank you Tim for your reply.

    I think that there is a general confusion about virtual drives and physical drives. I was refering to physical drives wondering if that model would be better (one physical drive for each function) or if it would be ok to have raid1 for host os and Raid 10 for everything else. Also would it make any difference if I create multiple partitions on Raid 10 instead of placing everything in one big drive. Page file on separate drive so that it can be excluded from replication. Still not sure if I need a separate physical drive a separate vhdx on a Raid 10 or a separate partion that will have the vhdx.

    Could someone out there given the information I provided give me some specifics. How many drives typr of Raid etc.

    Thanks,

    Leo

    1) Partitions are NOT going to help. Do RAID10 and wide striping so VM will get distributed between many spindles and that would be the way to boost IOPS. Think about SAS.

    2) Paring is nearly a pure sequential read and write operation so it cares about linear read and write performance and not IOPS. Stick with a fast SATA here. 


    StarWind iSCSI SAN & NAS

    giovedì 26 settembre 2013 10:32
  • Thans for your reply.

    I was under the impression that you can not start a VM from SAS.

    giovedì 26 settembre 2013 14:39
  • I think you keep bouncing back and forth between what is on the host and what the VMs are using.  You should let the host own all the physical drives.  Use RAID10 as was suggested for the volume on which you will store the virtual hard drives to be used by the VMs.  Yes, the VM, by default, will use IDE for boot, but that is within the virtual environment.  The VM has absolutely no idea what the physical storage is - SATA, SAS, flash, etc.  Hyper-V will simply create a file that is a virtual hard drive on the physical storage owned by the Hyper-V host.  The use cases for a VM to directly access a physical drive are very few and very far between.  Nothing you have described here indicates any need for a VM to have access to a physical drive.

    .:|:.:|:. tim

    giovedì 26 settembre 2013 16:30
  • So if I understood correctly I can have a SAS Raid 10 and have the host plus the virtual machines starting from SAS Raid 10.

    Correct?

    giovedì 26 settembre 2013 16:39
  • So if I understood correctly I can have a SAS Raid 10 and have the host plus the virtual machines starting from SAS Raid 10.

    Correct?

    VMs have no idea about the underlying storage stack characteristics on host. That's one of the things virtualization is for.

    StarWind iSCSI SAN & NAS

    giovedì 26 settembre 2013 19:37