Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!


Soft RAID 1 very slow
New on LowEndTalk? Please Register and read our Community Rules.

All new Registrations are manually reviewed and approved, so a short delay after registration may occur before your account becomes active.

Soft RAID 1 very slow

dnwkdnwk Member

I was running Proxmox on a software RAID 1. It was extremely slow on IO speed. Inside KVM VM with Virto and directsync, it could only achieve 1MB/s at most. Anyone know why?

Comments

  • perennateperennate Member, Host Rep

    What is 1 MB/s? There's many possible metrics for disk performance.

    Also, what's the disk performance on the host node like?

  • dnwkdnwk Member

    @perennate said:
    What is 1 MB/s? There's many possible metrics for disk performance.

    Also, what's the disk performance on the host node like?

    io speed

  • perennateperennate Member, Host Rep

    dnwk said: io speed

    good point.

  • SpeedBusSpeedBus Member, Host Rep

    Maybe the disks are syncing? Checkout

    cat /proc/mdstat

  • dnwkdnwk Member
    edited July 2014

    @SpeedBus said:
    Maybe the disks are syncing? Checkout

    cat /proc/mdstat

    Sync is completed

    The KVM VM is running windows

  • perennateperennate Member, Host Rep

    You still haven't said what disk performance on host is like, what kind of test you're doing and seeing 1 MB/s (no, io speed doesn't mean shit). Also what's disk cache setting in VM?

  • dnwkdnwk Member

    @perennate said:
    You still haven't said what disk performance on host is like, what kind of test you're doing and seeing 1 MB/s (no, io speed doesn't mean shit). Also what's disk cache setting in VM?

    I am using Direct Sync.

    ON host
    dd
    1073741824 bytes (1.1 GB) copied, 7.34427 s, 146 MB/s

    oops.... I just wipe my server with dd.......

    Thanked by 1sundaymouse
  • @dnwk said:
    oops.... I just wipe my server with dd.......

    I.. I don't even... How.. sigh.

  • @dnwk said:
    I was running Proxmox on a software RAID 1. It was extremely slow on IO speed. Inside KVM VM with Virto and directsync, it could only achieve 1MB/s at most. Anyone know why?

    I don't know the specifics of your hardware setup and what specific test you are using but I don't see that issue at all with Proxmox + Software RAID 1.

  • dnwkdnwk Member

    @0xdragon said:

    what's the correct command to test IO speed with DD?

  • lbftlbft Member

    dnwk said: what's the correct command to test IO speed with DD?

    dd if=/dev/null of=/dev/null bs=64k count=16k conv=fdatasync

  • perennateperennate Member, Host Rep

    lbft said: dd if=/dev/null of=/dev/null bs=64k count=16k conv=fdatasync

    You need to specify of file to use fdatasync, otherwise I get error:

    dd: fsync failed for ‘/dev/null’: Invalid argument

  • dnwkdnwk Member

    @perennate said:

    I don't quite understand of= and use of=/dev/sda1 so hard drive wiped.

  • perennateperennate Member, Host Rep

    dnwk said: I don't quite understand of= and use of=/dev/sda1 so hard drive wiped.

    Yeah you shouldn't run anything as root. Always use test account. Only root would be able to write to disk directly. And of can be device or regular file, when you set regular file you can do test of sequential read/write speed on top of the filesystem. Did you lose important data or what? Otherwise just reinstall OS o_O

  • edanedan Member

    The command usually use is:

    dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync

    Remember to delete the test file created.

  • dnwkdnwk Member

    From Windows Assessment, Disk Sequential 64 Read 535 MB/s Disk Random 16 Read 1.94MB/s

Sign In or Register to comment.