mfgoenk
Contributor
Contributor

low I/O performance after getting the VM more than 2048 GB RAM (VMware Server)

Hi all,

sorry i don`t know if it has ben asked bevor but i did not find this question in the forum. I have the following problem:

I have an VM with the following configuration:

  • First hdd is a virtuall one with 50 gb splitted into 2 GB files

  • Second and 3 hdd is an iscs lun on a san.

When i give the vm an amount of ram between 384 and 2048 mb ram it has great performance. i/o is about 600 mb/s on the vm hdd and stabel about 50 mb/s on the iscsi hdd`s.

Now i want to install oracle on the vm and my oracle guys told me the want sa much ram as possible.

I thought no prob and gave the vm 3600 mb ram. After rebooting the complete host with all of his vm`s gets very slow. I found out that i the i/O gets down on the vm from 600 to 200 on the vm hdd and from 50 stable to 10-15 unstable on theiscsi hdd`s. It dosen`t matter how much ram i give the vm. It can be a value from 384 to 2048 and i/o is perfectly, but what is casing this slow i/o on the host when giving the vm more than 2048 mb ram. I don`understand this.

My config is:

2 x Supermicro Server with 16 GB RAM and XÈON Proz. connected via FC to an Supermicro SAN with 16 HDD`S in an RAID 5.

Can anyone help me?

Greetings

Michael

Message was edited by: Ken.Cline to include VMware Server in subject

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4 Replies
weinstein5
Immortal
Immortal

How many other vms do you have running on this host?

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mfgoenk
Contributor
Contributor

there are running 4 other vm`s. all vm`s on this host are using 9 gb ram together and they are allowed to swap some memory. there are also 7 gb left for the host.

greetings

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Ken_Cline
Champion
Champion

What VMware product are you using? What is your host OS?

Ken Cline

Technical Director, Virtualization

Wells Landers

VMware Communities User Moderator

Ken Cline VMware vExpert 2009 VMware Communities User Moderator Blogging at: http://KensVirtualReality.wordpress.com/
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mfgoenk
Contributor
Contributor

VMware 1.04 and Windows2003 R2 SP2 with all Hotfixes 64 Bit

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