Solved

Debian Drive transfer speed on VMware ESX

Posted on 2011-03-09
7
650 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
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 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 500 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
 Database Backup and Recovery Best Practices

Join Percona’s, Architect, Manjot Singh as he presents Database Backup and Recovery Best Practices (with a Focus on MySQL) on Thursday, July 27, 2017 at 11:00 am PDT / 2:00 pm EDT (UTC-7). In the case of a failure, do you know how long it will take to restore your database?

 
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

Get MongoDB database support online, now!

At Percona’s web store you can order your MongoDB database support needs in minutes. No hassles, no fuss, just pick and click. Pay online with a credit card. Handle your MongoDB database support now!

Question has a verified solution.

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

HOW TO: Upload an ISO image to a VMware datastore for use with VMware vSphere Hypervisor 6.5 (ESXi 6.5) using the vSphere Host Client, and checking its MD5 checksum signature is correct.  It's a good idea to compare checksums, because many installat…
In this article, I will show you HOW TO: Perform a Physical to Virtual (P2V) Conversion the easy way from a computer backup (image).
Teach the user how to configure vSphere clusters to support the VMware FT feature Open vSphere Web Client: Verify vSphere HA is enabled: Verify netowrking for vMotion and FT Logging is in place or create it: Turn On FT for a virtual machine: Verify …
How to Install VMware Tools in Red Hat Enterprise Linux 6.4 (RHEL 6.4) Step-by-Step Tutorial

634 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