How to improve disk I/O performances with VMware Workstation

Posted by virtualization.info Staff   |   Monday, November 21st, 2005   |  

Even on a 2 GB RAM workstation (as mine) VMware virtual machines can run slowly. Too slowly sometimes.

This can depend on a large amount of factors but we can reduce the number to 4 critical issues:

  1. Antivirus real-time protection
    You probably run VMware Workstation on your everyday working computer, and you probably want to stay secure running an antivirus software.

    The most useful feature of any AV is the real-time protection, catching and monitoring I/O accesses of every process for suspicious activities.
    This feature can greatly impact on your VMs performances and should be fine-tuned for virtualization.

    So be sure to create an exclusion filter on your real-time protection settings for .vmdk (VMware virtual disk) and .vmem (VMware virtual memory) files. In this way countinous I/O operations on your virtual machines will not be hit by antivirus checking.

    Note: if you plan to run liveCD operating systems (like Knoppix) inside your VMs or simply often use CD images for installing new software, I highly recommend to exclude .iso files too from AV checking.

  2. HostOS disk fragmentation
    A really performance hitter for virtual machines is a fragmented host OS disk.

    VMs virtual disks are very large (4 GBs at minimum on the average) and are created by default as non preallocated. In other words your virtual disk grow as you install more software on the guest OS till reaching your defined disk limit.
    If you use only one physical disk for everyday work and VMs storing, you probably will use space around a growing virtual disk, obliging your host OS to fragment virtual machines more and more.

    So be sure to:

    • Create a dedicated partition for virtual machines only
    • Create guest OSes virtual disks with Allocate all disk space now option
    • Schedule a daily defragmentation for your virtual machines directories (maybe at launch time or during the night)
  3. Memory trimming
    Workstation checks which part of the guest OS virtual memory is not used and allocates it back to the host OS. This permits to have more concurrent virtual machines running but everytime the guest OS asks back for its memory it suffers a performance degradation.

    So, if you have enough free RAM for all planned concurrent VMs, be sure to disable memory trimming for guest OSes adding the following line to the virtual machine configuration (.vmx) file:

    MemTrimRate=0

    Note: Memory trimming can be disabled through GUI since Workstation 6.0.

  4. Page sharing (quoted from VMware documentation)
    VMware uses a page sharing technique to allow guest memory pages with identical contents to be stored as a single copy-on-write page. Page sharing decreases host memory usage, but consumes system resources, potentially including I/O bandwidth.

    You may want to avoid this overhead for guests for which host memory is plentiful and I/O latency is important. To disable page sharing, add the following line to the virtual machine configuration (.vmx) file:

    sched.mem.pshare.enable=FALSE option

These suggestions will work well for every VMware Workstation 5.x and Player 1.x since both share same engine.


Labels: ,

blog comments powered by Disqus


virtualization.info Newest articles
Release: Citrix XenApp and XenDesktop 7.6

September 30th, 2014

As announced in august, Citrix has now made available version 7.6 of its Virtual Desktop Infrastructure (VDI) product XenDesktop and desktop and virtualization product XenApp.
Version 7.6 contains the following…

Lenovo closes acquisition of IBM’s x86 Server Business

September 29th, 2014

While the fact that Lenovo would take over the x86 Server Business line from IBM isn’t new, today Lenovo announced that a definitive agreement has been made effective October 1st….

Release: Pivotal CF 1.3

September 29th, 2014

The Pivotal Initiative is the organization, born in December 2012 from the merge of EMC and VMware cloud application and big data offerings and well known for Pivotal CF…

Paper: IBM Flex System Solution for Microsoft Hyper-V (2-node) Reference Architecture

September 29th, 2014

IBM has released a paper titled: "IBM Flex System Solution for Microsoft Hyper-V (2-node) Reference Architecture". The paper which contains 50 pages describes a reference architecture for building a 2…

Book: Virtualization 2.0 for dummies

September 29th, 2014

VMware has released a free eBook titled: "Virtualization 2.0 for dummies". The book which contains 88 pages can be downloaded from the VMware website after registration.
The book covers the…

Paper: VMware Virtual SAN Performance with Microsoft SQL Server

September 29th, 2014

VMware has released a paper titled:"VMware Virtual SAN Performance with Microsoft SQL Server", the paper which contains 9 pages shows the result of a scalability study running Microsoft SQL Server…

Release: Oracle OpenStack for Oracle Linux (O3L) 1.0

September 25th, 2014

Oracle has released its Oracle OpenStack for Oracle Linux (O3L). Oracle OpenStack for Oracle Linux is a distribution of the OpenStack (Icehouse) cloud framework integrated with the Oracle Linux Operating…

Paper: VMware Horizon 6 Reference Architecture

September 24th, 2014

VMware has released a paper titled: "VMware Horizon 6 Reference Architecture". The paper which contains 53 pages describes a reference architecture for building a VMware Horizon 6 deployment supporting 2,000…

Microsoft releases new Azure Virtual Machine sizes

September 24th, 2014

Microsoft has released new VM sizes for Microsoft Azure Virtual Machines and Web/Worker roles. The new VM sizes are called D-Series offering up to 112 GB in memory with compute…

Citrix releases tech preview of XenDesktop Windows Azure Pack Gallery Image

September 24th, 2014

Citrix has released a technical preview of a Gallery Image containing XenDesktop 7.5 to be used within Microsofts Windows Azure Pack (WAP).
WAP emulates the Windows Azure experience on-premise so…

Oracle Board of Directors appoints ex CEO Larry Ellison as Executive Chairman and CTO

September 23rd, 2014

Oracle has caused a world wide earthquake with the latest news announcing a change in its management, Larry Ellison, one of the founders of the Oracle empire who remained the…

Red Hat acquires FeedHenry

September 19th, 2014

We are living in a mobile world and the future will be more wireless than ever, we are working with technology all the time using our smartphones and tablets, the…

Citrix acquires Virtual

September 18th, 2014

Citrix yesterday announced that it has acquired Virtual. Virtual provides a virtualization platform for iOS and Android which is cloud based. Virtual provides a solution for testing applications without the…

Will HP buy VMware from EMC?

September 17th, 2014

Last week the New York times published an article titled: “EMC explores selling stake in VMware“. While the news that EMC is exploring selling VMware is not new though. Paul…

 
Monthly Archive