How fast is KVM?

C

cyberbootje

Member
Nov 29, 2009
77
0
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Hi

I currently am testing with a machine: intel core2duo 2.4Ghz, 8GB ram ECC and 4 x sata 250GB 7200Rpm in raid 5 with a 3ware raid controller.
I did a install of debian 5, allocated 5Gb to the KVM machine.

Disk type: VIRTIO
Format: raw
Guest type: 2.6
CPU socket: 1
Memory 512 mb

It took debian 5 ~6 minutes to just only format 5.4Gb for partitioning.
Is this acceptable? can it go faster? other settings maby?
 
This is the output when there are no VM's at all:

CPU BOGOMIPS: 9600.45
REGEX/SECOND: 783718
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 131.02 MB/sec
AVERAGE SEEK TIME: 11.10 ms
FSYNCS/SECOND: 115.21
DNS EXT: 46.24 ms
DNS INT: 21.86 ms (********)


This is the output when i am doing a format of 32Gb debian 5, cpu - 0% memory at 109mb:

CPU BOGOMIPS: 9600.45
REGEX/SECOND: 777946
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 45.26 MB/sec
AVERAGE SEEK TIME: 20.42 ms
FSYNCS/SECOND: 103.20
DNS EXT: 36.81 ms
DNS INT: 23.85 ms (*********)
 
cyberbootje said:
Hi

I currently am testing with a machine: intel core2duo 2.4Ghz, 8GB ram ECC and 4 x sata 250GB 7200Rpm in raid 5 with a 3ware raid controller.
I did a install of debian 5, allocated 5Gb to the KVM machine.

Disk type: VIRTIO
Format: raw
Guest type: 2.6
CPU socket: 1
Memory 512 mb

It took debian 5 ~6 minutes to just only format 5.4Gb for partitioning.
Is this acceptable? can it go faster? other settings maby?
Click to expand...

I just tested this on one of my test machines (single 500 gb sata drive).
format of the debian guest partition tooks 14 seconds.
 
cyberbootje said:
This is the output when there are no VM's at all:

CPU BOGOMIPS: 9600.45
REGEX/SECOND: 783718
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 131.02 MB/sec
AVERAGE SEEK TIME: 11.10 ms
FSYNCS/SECOND: 115.21
DNS EXT: 46.24 ms
DNS INT: 21.86 ms (********)


This is the output when i am doing a format of 32Gb debian 5, cpu - 0% memory at 109mb:

CPU BOGOMIPS: 9600.45
REGEX/SECOND: 777946
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 45.26 MB/sec
AVERAGE SEEK TIME: 20.42 ms
FSYNCS/SECOND: 103.20
DNS EXT: 36.81 ms
DNS INT: 23.85 ms (*********)
Click to expand...

very bad FSYNCS/SECOND: 115.21.

you do not have write cache on the raid controller enabled.

=> activate it and make sure you have a BBU - otherwise you could loose data in the case of a powerloss.
 
Well i disabled it, yes... why? i have no BBU.
But that is the only problem?

Can KVM compete with vmware esx in speed?
 
cyberbootje said:
Well i disabled it, yes... why? i have no BBU.
But that is the only problem?

Can KVM compete with vmware esx in speed?
Click to expand...

basically in almost all virtualization scenarios io is the bottleneck. so if you have a slow io system (and this is slow) you will loose a lot. its just like driving a car in low gear on the highway - makes no sense at all.

ESX/KVM: KVM is faster. Redhat publishes a lot of information about this (just google) - But take care, there is more or less no real independent benchmark available and its quite hard to make good benchmarking.

vmware manages to publish always benchmarks showing that they are doubling their performance in each release - like Apple, each new notebook is always 3 times faster than the previous one.

But anyway, these are marketing figures - test by yourself.

I just noticed that you also have this issue:
http://www.proxmox.com/forum/showthread.php?t=2716

and it looks that there is still something not working as expected on your installation.
 
cyberbootje said:
What machine did you use?
Click to expand...

one of my test machines:

  • Intel(R) Xeon(R) CPU X3220
  • Single WD 500 GB sata (RE2)
  • INTEL S3210SHLC Server Board
  • 8 gb ram
 
tom said:
very bad FSYNCS/SECOND: 115.21.

you do not have write cache on the raid controller enabled.

=> activate it and make sure you have a BBU - otherwise you could loose data in the case of a powerloss.
Click to expand...

That looks very strange even for raid 5 without write cache. I've got similar output on one old PATA drive. You could try doing hdparm -tT /dev/<drive> and check is it really a drive problem.

PS: are you sure that your raid isn't degraded?
 
No it isn't, i just did a fresh raid build.
Now i am doing it again but with write cahce enabled, without BBU but that doesn't matter now.

I have to say it was degraded when i pulled it out of the Datacenter but after a clean raid setup there was no prob.
Maby i will go buy some new disks today, these are 250Gb i need more space.

When it is finished with a write cache enabled i will post the outcome.

P.S.
I did try a stand alone disk, no raid and it still gave a FSYNCS/SECOND: 120.01.
 
cyberbootje said:
No it isn't, i just did a fresh raid build.
Now i am doing it again but with write cahce enabled, without BBU but that doesn't matter now.

I have to say it was degraded when i pulled it out of the Datacenter but after a clean raid setup there was no prob.
Maby i will go buy some new disks today, these are 250Gb i need more space.

When it is finished with a write cache enabled i will post the outcome.

P.S.
I did try a stand alone disk, no raid and it still gave a FSYNCS/SECOND: 120.01.
Click to expand...

if a standalone disk gives such low fsync its the same issue. cache disabled. (every harddisk has a built in cache).

my single sata (with cache enabled):
Code: 
proxmox-105:~# pveperf
CPU BOGOMIPS:      19152.00
REGEX/SECOND:      805466
HD SIZE:           94.49 GB (/dev/pve/root)
BUFFERED READS:    76.69 MB/sec
AVERAGE SEEK TIME: 9.59 ms
FSYNCS/SECOND:     1136.51
DNS EXT:           26.68 ms
DNS INT:           1.04 ms (proxmox.com)
proxmox-105:~#

especially sata disks for raid systems usually has this disabled to prevent data loss. consumer disk always has cache enabled.
 
Ok i made an raid 5 array with write cahce enabled, no BBU
Here the tests:

No machines running:

vx00vm03:~# pveperf
CPU BOGOMIPS: 9604.10
REGEX/SECOND: 782118
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 159.20 MB/sec
AVERAGE SEEK TIME: 10.31 ms
FSYNCS/SECOND: 1868.72
DNS EXT: 44.93 ms
DNS INT: 27.40 ms (**********)
vx00vm03:~# pveperf
CPU BOGOMIPS: 9604.10
REGEX/SECOND: 789045
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 130.27 MB/sec
AVERAGE SEEK TIME: 10.50 ms
FSYNCS/SECOND: 1273.60
DNS EXT: 78.99 ms
DNS INT: 35.26 ms (*********)

1 Machine running and was formatting 32Gb:

vx00vm03:~# pveperf
CPU BOGOMIPS: 9604.10
REGEX/SECOND: 798525
HD SIZE: 94.49 GB (/dev/pve/root)
BUFFERED READS: 109.88 MB/sec
AVERAGE SEEK TIME: 22.06 ms
FSYNCS/SECOND: 281.59
DNS EXT: 107.94 ms
DNS INT: 42.81 ms (***********)


Formatting 5.4 Gb now took ~ 30 seconds.
Now it is quite ok i think? or can it go faster?

I do want ISCSI or something so what is the best?
 
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