Gear
Contributor
Contributor

Performance Problems under Raid 5

Hello together,

maybe somebody can help me to solve my absolutley bad performance problems.

The system is based upon:

Core 4 processor

4GB RAM

3Ware 9650 Raid Controller

Raid 5 Array >800GB

Fedora 7 as Host System

VM Workstation 6

Suse 10.2 and Vista Guests

The performance in the guest systems is absolutely bad, so that normal working

isn't possible.

I tried to find, who's responsible for that performance problems and found out, the

the disk system is the bottleneck.

In the Hostsystem i get with hdparm -t a respone of about 180 MB/s. That's a

good value for Raid 5.

In the guest systems I get with hdparm -t about 5 MB/s. This is more than worse.

An additional physical disk directly integrated and connected gives me about

40 MB/s, that's also ok.

It is also interesting, that a direct access from the guests on the raid 5 system

(without virtual disks), gives the same bad performance results.

I do not have a clue what I can do with this problems?! Please help.

Thx, Gear

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15 Replies
oreeh
Immortal
Immortal

Please provide some more details about the guests.

Are the guests configured to use vSMP?

How much memory did you allocate to the guests?

How much memory is configured for Workstation?

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Gear
Contributor
Contributor

There are different guests installed.

4 Linux guests with 256MB and 512MB and 756MB Memory

1 Windows Vista with 1,5GB Memory

I didn't configured explicit memory for the Workstation, how can I do that?

It seems that neither the host nor the guests are swapping.

The Windows guest has two Processors assigned, but I didn't have

implemented any additional things like vSMP.

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oreeh
Immortal
Immortal

I didn't configured explicit memory for the Workstation, how can I do that?

What is configured in "Edit - Preferences - Memory"?

The Windows guest has two Processors assigned, ...

This IS vSMP.

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Gear
Contributor
Contributor

yes, you are right!

sorry for late answering, but I was outside and didn't had access to the machine.

So the answer for configured memory as you described ist 2961 MB. Furthermore

Allow some virtual machine memory to be swapped is activated.

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oreeh
Immortal
Immortal

Are all these guests running at the same time?

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devzero
Expert
Expert

shutdown all VMs (especially vista) and study performance of the single one.

furthermore, fedora isn`t supported as host os

Gear
Contributor
Contributor

yes, all guests are running at same time.

As I remember, I tried to run perfomance test with only one running system,

but it didn't show much better results.

I will try it again and will send you the results.

Your input with the OS is fair. How strong would you rate the propability the

the Fedora OS can cause these problems? Because the efforts in setting up

the whole system (Lan Adapters, their assignments, .....) are high. Or do you

have an idea for as smart way of doing that?

Is there an OS which you can recommend?

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Gear
Contributor
Contributor

yes, all guests are running at same time.

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Gear
Contributor
Contributor

very strange,

when I shutdown the Vista Host, then the performance raises up.

The measurement result for the DC1 guest(SUSE 10.2):

63MB/s Vista guest off

602 kB/s Visto guest on

68MB/s Vista guest off

But after booting the Vista

guest I waited until

there was no hdd activity.

....??

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Gear
Contributor
Contributor

pleease have a look at my problem

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Gear
Contributor
Contributor

please have a look at my problem

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ksc
VMware Employee
VMware Employee

The Windows guest has two Processors assigned, but I didn't have

implemented any additional things like vSMP.

vSMP has some rather unpleasant scheduling side effects - virtual CPUs can get out of sync, and out of sync virtual CPUs cause other things (like virtual disks) to run much more slowly than normal. These side effects show up most prominently when the host is overcommitted (e.g. running more virtual CPUs and host programs than it has real CPUs).

The best advice is to not assign two processors to a VM unless you absolutely need it. ESX can efficiently run multiprocessor VMs; hosted products sometimes can, and sometimes cannot.

Gear
Contributor
Contributor

on thefirst sight it looked well.After 20sec booting, the logon screen appearsafter one min vista booting averything looks fineDuring the boot process averything looks fine on the linux guest performance measurebut when vista cames up after the logon process the perofrmance ist down...until vista is turned off

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Gear
Contributor
Contributor

It is a hint!! The performance improved on the linux guest (where I measure the performance) up to 15Mb/s.

But is still far away from the 60 when the Vista guest is turned off. I must not mentioned the performance

in the vista guest is also terrible Smiley Wink

I measure:with vista online:PC1 (DC1) 15MB/sPC2(FW) 675Kb/sPC3(Gateway) 1,2MB/Swith Vista offlinePC1 15MB/SPC2 63,3 MB/SPC3 63,8 MB/s

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Gear
Contributor
Contributor

The problem seems to be the Host System under Fedora!

I changed the OS to Open Suse 10.3 and the performance problem seems to be away.

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