On 27/07/2015 6:54 PM, Donny Davis wrote:
Add this on to your dd command
conv=sync
On the console login of my host/server, the 'dd' command I used was: dd bs=1M count=256 if=/dev/zero of=test conv=fdatasync Would I be replacing the 'conv=fdatasync' with the 'conv=sync', or am I appending it (i.e., 'conv=fdatasync,sync')
And then report result. Its no surprise that your writes are slow in raid1
I will give it a try and report results when I re-install my oVirt+Hosted Engine on my host, however it actually, wasn't/isn't the write speed on the bare metal host that I was too concerned with but rather the poor write speed within the guest VMs, particularly my Windows 7 guest. As you can see from my original results, within the Win7 guest on oVirt I was only getting about 10 MByte/s while the host I was able to get about 74 MByte/s. That just seems like one heck of a performance drop-off to me, which means I either don't have something configured/tuned properly, or virtio-SCSI is not that good (though everything I have rad suggests that virtio-SCSI is what I should be using for best performance, as long as the guest drivers are installed) -Alan
Hello,
I am running oVirt 3.5 on a single server (hosted engine). I have two Western Digital WD20EZRX drives in a hardware RAID1 configuration. My storage is actually on the single server, but I am attaching to it via NFS.
I created a Windows 7 guest, and I am finding its write speeds to be horrible. It is a VirtIO-SCSI drive and the guest additions are installed.
The installation of the OS took way longer than bare metal or even VMware. When I ran Windows updates, it again took a *lot* longer than on bar metal or on VMware.
The read speeds seem to be fine. The guest is responsive when I click on programs and they open about as fast as bare metal or VMware.
I downloaded and ran "Parkdale" HDD tester and ran a test with the following settings:
- File size: 4000 - Block Size: 1 MByte
The results are as follows:
- Seq. Write Speed: 10.7 MByte/sec (Random Q32D: ) - Seq. Read Speed: 237.3 MByte/sec (Random Q32D: )
I ran another test, but this time changing the "Block Size" to "64 kByte [Windows Default]". Results are as follows:
- Seq. Write Speed: 10.7 MByte/sec (Random Q32D: ) - Seq. Read Speed: 237.3 MByte/sec (Random Q32D: )
On the host, running '|dd bs=1M count=256 if=/dev/zero of=test conv=fdatasync|' on my data mount via NFS rsuled in the following:
256+0 records in 256+0 records out 268435456 bytes (268 MB) copied, 3.59431 s, 74.7 MB/s
I got this <https://romanrm.net/dd-benchmark> <https://romanrm.net/dd-benchmark> and measures the write speed of a disk. As you can see, it is significantly higher than what I am getting in the Windows guest VM.
Running that same "dd" test on an Ubuntu guest VM gives me 24MB/s.
Any ideas why I have such poor write performance? Is this normal with oVirt guests? Any ideas on what I might be able to do to improve them? I don't expect to get close to the "bare metal" results, but maybe something in the 40-60 MB/s range would be nice.
Thanks, in advance, for your help and advice.
-Alan
_______________________________________________ Users mailing list Users@ovirt.org <mailto:Users@ovirt.org> http://lists.ovirt.org/mailman/listinfo/users