Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Debian Drive transfer speed on VMware ESX

Posted on 2011-03-09
7
Medium Priority
?
661 Views
Last Modified: 2012-05-11
Hi all

I have an unusual problem with Disk transfer speeds on a virtual Linux environment.

This environment consists of an ESX host running 3i, 3.5.0, 153875 and 2 Debian 5.0 Linux virtual machines.

When booting the machines have a hdparm transfer rate output of:

 /dev/sda:
 Timing cached reads:   1418 MB in  2.00 seconds = 707.95 MB/sec
 Timing buffered disk reads:  132 MB in  3.01 seconds =  43.93 MB/sec

After a couple of days, the machines become sluggish and the same test produces:

/dev/sda:
 Timing cached reads:   162 MB in  2.00 seconds =  80.99 MB/sec
 Timing buffered disk reads:   12 MB in  3.78 seconds =   3.18 MB/sec


The command that is being run is hdparm -tT /dev/sda

Any ideas on why this is occurring, I cant see anything obvious in the logs that will cause this.
0
Comment
Question by:alexanderfoti
  • 4
  • 3
7 Comments
 
LVL 28

Expert Comment

by:bgoering
ID: 35083242
Is your vm configured with IDE drives?
0
 
LVL 1

Author Comment

by:alexanderfoti
ID: 35083317
No its an ESX server, you are only able to choose SCSI Devices.
0
 
LVL 28

Accepted Solution

by:
bgoering earned 2000 total points
ID: 35083467
Ah, I see it is 3.5 (you can use IDE drives on 4.1). I am unable to recreate this issue on 4.1 but I suggest you take a look at http://communities.vmware.com/message/1077902#1077902, and in particular if you have a vSMP vm try it with a single virtual cpu (or disable the page sharing as in http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004901) On 3.5 the overhead of manageing vSMP was a bit higher than on 4.x, and sometimes one could realize a huge performance increade by reducing to a single vCPU.

Here are the results from one of my 2 vCPU mail servers that has been up for a while now on ESX 4.1:
[root@prodvmail01 ~]# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   2396 MB in  2.00 seconds = 1197.89 MB/sec
 Timing buffered disk reads:  496 MB in  3.01 seconds = 164.95 MB/sec
[root@prodvmail01 ~]# uptime
 08:51:40 up 773 days, 11:37,  3 users,  load average: 0.14, 0.08, 0.04
[root@prodvmail01 ~]#


0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 1

Author Comment

by:alexanderfoti
ID: 35084455
Many Thanks.

I have turned off VSMP on both boxes and have restarted them. Now all we have to do is wait until they slow down again now!

I have also removed more than one core from the virtual machines, so at the moment, they only have 1 core each.
0
 
LVL 28

Expert Comment

by:bgoering
ID: 35084951
Sounds good - keep us posted
0
 
LVL 1

Author Comment

by:alexanderfoti
ID: 35093324
Bad news - HDparm results today:

/dev/sda:
 Timing cached reads:   1394 MB in  2.00 seconds = 695.98 MB/sec
 Timing buffered disk reads:    8 MB in  3.81 seconds =   2.10 MB/sec

Any ideas?
0
 
LVL 1

Author Comment

by:alexanderfoti
ID: 35201391
After restarting the host, it appears the drive speeds have now returned to normal. Many thanksk
0

Featured Post

Important Lessons on Recovering from Petya

In their most recent webinar, Skyport Systems explores ways to isolate and protect critical databases to keep the core of your company safe from harm.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article outlines why you need to choose a backup solution that protects your entire environment – including your VMware ESXi and Microsoft Hyper-V virtualization hosts – not just your virtual machines.
This article will show you step-by-step instructions to build your own NTP CentOS server.  The network diagram shows the best practice to setup the NTP server farm for redundancy.  This article also serves as your NTP server documentation.
Teach the user how to edit .vmx files to add advanced configuration options Open vSphere Web Client: Edit Settings for a VM: Choose VM Options -> Advanced: Add Configuration Parameters:
Teach the user how to use vSphere Update Manager to update the VMware Tools and virtual machine hardware version Open vSphere Client: Review manual processes for updating VMware Tools and virtual hardware versions: Create a new baseline group in vSp…
Suggested Courses

926 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question