Preparing to install

Discussion in 'Proxmox VE 1.x: Installation and configuration' started by GarthK, Feb 27, 2009.

  1. GarthK

    GarthK Member

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    I'm getting ready to install v1.1 but I have one more question. I have six 500GB spindles attached to a 3Ware 9550SXU RAID card and I would like to split them into two RAID 5 groups of three drives each, having v1.1 take over the first group and leaving the second group for me to use with Samba as a share.

    If I let the v1.1 CD complete the install, will it only overwrite the first group and leave the second group alone?

    Thanx,
    Garth
     
  2. tom

    tom Proxmox Staff Member
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    first: raid5 is slow in write speed, but this is another story.

    if you install, you can select the hard disk for installation. (means your raid volume). the second one should not be touched.
     
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  3. GarthK

    GarthK Member

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    Thanx for the quick reply. I understand about RAID 5 performance but until I upgrade to 1TB spindles, other RAID types use too much overhead. I may take your advice anyhow, we'll see.

    Thanx again,
    Garth
     
  4. tom

    tom Proxmox Staff Member
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    why not raid10 with 6 disks? during install make a smaller root partitions (to maximize data partition).

    the samba shares can be under: /var/lib/vz/ (this is the data partition)

    I assume raid10 with 6 disk is way faster than raid5.
     
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  5. GarthK

    GarthK Member

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    The main reason is that RAID 5 costs me 500GB in overhead out of 3TB while RAID 10 costs me 1.5TB of overhead. Secondly, I know that RAID 5 has a bad rap when it comes to write performance but I'm not sure that the literature/benchmarks back that reputation up. Lastly, this is a machine I rebuild frequently so performance is not critical. I'll load v1.1 on it soon, replacing VMWare Server 2.0, but will probably load on top of that when something else interesting comes along (ESXi?). Nothing against v1.1, I do this for fun. I am looking forward to v2.0 and will give it a try when it becomes available as well.

    Thanx,
    Garth
     
  6. tog

    tog Member

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    You actually gain a very good amount of performance by using RAID10 versus RAID5. Not necessarily for unrealistic single-task sequential reads, but for the absolute most common every day random I/O it's the difference between the random iops speed of a single disk with RAID5 versus the random iops speed of 3 disks with RAID10.

    Try it, play with it both ways and see for yourself. Use bonnie to give you an idea of your performance difference with one configuration vs. the other.

    If you care far more about amount of space, RAID5 is fine. If you do actually want extra disk performance out of your setup you'll want RAID10.

    A bit off-topic for a Linux-related forum, but using ZFS I actually compromised and ended up with awesome performance (500MB/s, ~2000 iops) by creating five 3-disk RAID5's and striping them together. That's five sets of 3 disks each, losing 1/3 of my space but much better performance for it. You probably can't do that sort of setup with a normal hardware RAID controller, though. If that configuration was possible with the 3ware controller, you could compromise in exactly the same way, double your iops by doing two 3-disk RAID5's striped together.
     
  7. GarthK

    GarthK Member

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    Sounds interesting and I may give it a try just to see what happens. I just came across a 3Ware white paper on performance optimization and it gave me a couple of things to look at, particularly wrt transfer block size which I currently have at the default. More fun stuff to play with! Now if I could just convince my wife that 1TB spindles are "way more better" than 500GB ones, I'd be home free! :)

    One last q: I think I've read/been told that the default for kvm-type vm's (windows xp, 2003...) is a single, growable disk. Is that correct?

    Thanx,
    Garth
     
  8. tog

    tog Member

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    Yes, the default format for KVM is a virtual disk stored inside a ".qcow2" file which starts small and grows as you actually put real data on it.
     
  9. GarthK

    GarthK Member

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    One question leads to another...

    I want to install VE on a smaller box with two drives. Can I tell VE to use both drives during the install. I'm still searching the docs but haven't found anything about using multiple drives without first having some sort of RAID card.

    Thanx,
    Garth
     
  10. tom

    tom Proxmox Staff Member
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    no, only one disk (or one disk array) is used. as we have already LVM2, you can add whatever you want but you need to understand LVM.

    for 2.0, a more flexibly system will be introduced, means you can add the second drive as an additional storage (e.g. for VM´s) - also remote storage can be added.
     
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  11. GarthK

    GarthK Member

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    No prob. I've already swapped the drive for a 500GB spare I had laying around and have loaded VE.

    Next Q: every time I try and download a template from ProxMox, I get a 404 - file not found after it successfully makes a connection.

    What am I doing wrong?

    Thanx,
    Garth
     
  12. GarthK

    GarthK Member

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    It seems to download directly thru my browser just fine so I'll try using it that way.

    Thanx,
    Garth
     
  13. fromport

    fromport Member

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    I asked the same question last week.
    I looked for (and couldn't find it in) the FAQ and/or the documentation.
    http://proxmox.com/forum/showthread.php?t=1074

    The answer:
    use '# pveam update'

    Fromport
     
  14. GarthK

    GarthK Member

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    "pveam update" worked like a charm.

    Thanx,
    Garth
     
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