Hi,
You can try to enable IO threads and assign multiple Ceph disks to the
VM, then build some kind of raid0 to increase performance.
Generally speaking, a SSD based Ceph cluster is considered to perform
well when a VM gets about 2000 IOPS, and factors like CPU 1-thread
performance, network and disk have to be selected with care. Also
server's energy saving disabled, etc.
What CPUs in those 9 nodes?
Ceph is built for parallel access and scaling. You're only using 1
thread of your VM for disk IO currently.
Cheers
Eneko
El 17/3/20 a las 14:04, Rainer Krienke escribió:
Hello,
I run a pve 6.1-7 cluster with 5 nodes that is attached (via 10Gb
Network) to a ceph nautilus cluster with 9 ceph nodes and 144 magnetic
disks. The pool with rbd images for disk storage is erasure coded with a
4+2 profile.
I ran some performance tests since I noticed that there seems to be a
strange limit to the disk read/write rate on a single VM even if the
physical machine hosting the VM as well as cluster is in total capable
of doing much more.
So what I did was to run a bonnie++ as well as a dd read/write test
first in parallel on 10 VMs, then on 5 VMs and at last on a single one.
A value of "75" for "bo++rd" in the first line below means that each of
the 10 bonnie++-processes running on 10 different proxmox VMs in
parallel reported in average over all the results a value of
75MBytes/sec for "block read". The ceph-values are the peaks measured by
ceph itself during the test run (all rd/wr values in MBytes/sec):
VM-count: bo++rd: bo++wr: ceph(rd/wr): dd-rd: dd-wr: ceph(rd/wr):
10 75 42 540/485 55 58 698/711
5 90 62 310/338 47 80 248/421
1 108 114 111/120 130 145 337/165
What I find a little strange is that running many VMs doing IO in
parallel I reach a write rate of about 485-711 MBytes/sec. However when
running a single VM the maximum is at 120-165 MBytes/sec. Since the
whole networking is based on a 10GB infrastructure and an iperf test
between a VM and a ceph node reported nearby 10Gb I would expect a
higher rate for the single VM. Even if I run a test with 5 VMs on *one*
physical host (values not shown above), the results are not far behind
the values for 5 VMs on 5 hosts shown above. So the single host seems
not to be the limiting factor, but the VM itself is limiting IO.
What rates do you find on your proxmox/ceph cluster for single VMs?
Does any one have any explanation for this rather big difference or
perhaps an idea what to try in order to get higher IO-rates from a
single VM?
Thank you very much in advance
Rainer
---------------------------------------------
Here are the more detailed test results for anyone interested:
Using bonnie++:
10 VMs (two on each of the 5 hosts) VMs: 4GB RAM, BTRFS, cd /root;
bonnie++ -u root
Average for each VM:
block write: ~42MByte/sec, block read: ~75MByte/sec
ceph: total peak: 485MByte/sec write, 540MByte/sec read
5 VMs (one on each of the 5 hosts) 4GB RAM, BTRFS, cd /root; bonnie++ -u
root
Average for each VM:
block write: ~62MByte/sec, block read: ~90MByte/sec
ceph: total peak: 338MByte/sec write, 310MByte/sec read
1 VM 4GB RAM, BTRFS, cd /root; bonnie++ -u root
Average for VM:
block write: ~114 MByte/sec, block read: ~108MByte/sec
ceph: total peak: 120 MByte/sec write, 111MByte/sec read
Using dd:
10 VMs (two on each of the 5 hosts) VMs: 4GB RAM, write on a ceph based
vm-disk "sdb" (rbd)
write: dd if=/dev/zero of=/dev/sdb bs=nnn count=kkk conv=fsync
status=progress
read: dd of=/dev/null if=/dev/sdb bs=nnn count=kkk status=progress
Average for each VM:
bs=1024k count=12000: dd write: ~58MByte/sec, dd read: ~48MByte/sec
bs=4096k count=3000: dd write: ~59MByte/sec, dd read: ~55MByte/sec
ceph: total peak: 711MByte/sec write, 698 MByte/sec read
5 VMs (two on each of the 5 hosts) VMs: 4GB RAM, write on a ceph based
vm-disk "sdb" (rbd)
write: dd if=/dev/zero of=/dev/sdb bs=4096k count=3000 conv=fsync
status=progress
read: dd of=/dev/null if=/dev/sdb bs=4096k count=3000 status=progress
Average for each VM:
bs=4096 count=3000: dd write: ~80 MByte/sec, dd read: ~47MByte/sec
ceph: total peak: 421MByte/sec write, 248 MByte/sec read
1 VM: 4GB RAM, write on a ceph based vm-disk "sdb" (rbd-device)
write: dd if=/dev/zero of=/dev/sdb bs=4096k count=3000 conv=fsync
status=progress
read: dd of=/dev/null if=/dev/sdb bs=4096k count=3000 status=progress
Average for each VM:
bs=4096k count=3000: dd write: ~145 MByte/sec, dd read: ~130 MByte/sec
ceph: total peak: 165 MByte/sec write, 337 MByte/sec read
--
Zuzendari Teknikoa / Director Técnico
Binovo IT Human Project, S.L.
Telf. 943569206
Astigarragako bidea 2, 2º izq. oficina 11; 20180 Oiartzun (Gipuzkoa)
www.binovo.es
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