SCO on VMWare Server, performance

Posted on 2009-12-16
Last Modified: 2013-12-05

I am running SCO OpenServer 5.0.7 as a guest on VMware Server 1.0.10.  The host OS is CentOS 5.  The problem is that it is slow.  I realize that ESXi would be faster, but I am not quite ready to take that route yet. First I want to explore what I can do to speed up VMware Server - I believe it should run a lot faster than what it does.

I did a very simple benchmark test just using dd to read from the HD and send it to /dev/null.  This is a very limited benchmark, but should give me a decent, if crude, idea of the read performance.  I performed the test on three different servers, both from the Linux host OS and from the VMs.  

The result:
Old server with SCO installed directly on 6 year old H/W, Adaptec I2O Raid, 15K RPM SCSI disks:  31s.

Linux server (5 year old H/W, Adaptec I2O Raid, 15K RPM SCSI disks): 31s.
SCO VM running on above Linux server: 6m 25s

Linux server (1 year old H/W, Adaptec 2405 Raid, 7200 RPM SATA disks): 5s
SCO VM running on above Linux server: 1m 13s

So this benchmark takes 12-14 times longer on the VM than it does on the host OS.  Can this possibly be normal?  What can I do to speed this up?

Lastly, any chance that VMWare Server 2.0 would be faster?


Ps. There are no vmware tools for OpenServer 5.0.7.  Also, example of benchmark command: "time dd if=/dev/sda of=/dev/null bs=512 count=1953126"

Question by:Lars007
    LVL 29

    Expert Comment

    by:Michael W
    For one, I would recommend upgrading to VMware Server 2.0. It has a number of bug fixes, especially in the memory and CPU performance areas.

    As for the Host server, what kind of specs does it have? (i.e. CPU type, RAM, etc)

    Author Comment

    Got it.  I did not know that VMWare Server 2 had any performance benefits  (I searched for this, but came up with no such benchmarks).

    Specs on one of the servers I benchmarked with:
    CPU: Xeon X3360 Quad-Core Processor (2.83GHz/12MB/1333MHz/95W
    RAM: 4GB DDR-2/667GHz
    Mainboard: Supermicro X7SBL-LN2 Motherboard with Intel 3200 Chipset
    Adaptec 2405 RAID Controller
    7200 RPM SATA disks

    With this server, the dd-test from the CentOS host took 5s, while the same test from the SCO VM too 1m13s (x14 longer!).  It just seems abnormally slow.

    What can I do to speed this up?  


    Ps. I just ran the same test on a Linux VM on my ESXi 3.5 server (HP Proliant DL 380 G5), and it ran in just 15 s.  I might upgrade this to ESX4 and see if I can convert the VM to ESXi format and so forth, but that is a longer project (the business system running on the SCO VM has only been tested on VMWare Server 1 by the vendor, so if I am going to move it to ESXi 4, it will require thorough testing, etc.), and I really need to get the existing VMware Server solution up to a more acceptable speed in the meantime.
    LVL 24

    Expert Comment

    -Move all VMs to a dedicated disk for example USB drive off the disk where you installed the host OS. Same applies to different partition on the same disk as the host OS, move them to dedicated drive with dedicated spindle only for the VMs if possible do not store busy VMs on the same disk as other VMs
    -use raid eg. raid 5 or 10 if you have the budget
    -vmware tools must be installed
    -Create pre-allocated vmdk for all virtual disks
    -Set a fix paging file size for each guest OS
    -Disable unwanted service & theme in the guest OS
    -Remove unneeded virtual hardware such as serial/usb/parallel/floppy
    -add more physical ram to the host

    these are some of the common methods to improve performance on vmware server
    LVL 12

    Expert Comment

    I advice you to wait (don't upgrade vmware server from 1 to 2.x yet). Personally I am having a nightmare in performance now fighting with Vmware server after upgrading from 1.x to 2.x.

    You can see many posts on the internet talking about that, I didn't see any improvement upgrading from v.1 to v.2. Actually v.1 was very stable doing exactly what it is meant to.
    LVL 29

    Expert Comment

    by:Michael W
    I believe that under VMware Server 1.x, guest VMs are run in full virtualization mode. This means it attempts to make a total copy of the hardware in which the server is running from.

    Under Server 2.x and ESXi 3/4, you can use either full or para-virtualization.

    VMware :: Understanding Full Virtualization, Paravirtualization, and Hardware Assist

    Author Comment

    It sounds like, since SCO OpenServer 5.0.7 does not have vmware-tools, I am stuck with full virtualization mode.  So there seems to be no clear performance benefits of VMWare Server 2 (sometimes the opposite, per the above post), I can probably stick to VMWare Server 1 in my case.

    I forgot to mention that this VM is the only VM on this server (and the server's whole purpose is to host this one VM).

    Is it really normal for disk I/O to be 14x slower on the VM than it is on the host?  Are there any benchmarks confirming this?  Any settings, other than the ones already mentioned by ryder0707, that would improve performance without VMware tools installed?


    LVL 24

    Expert Comment

    vmware tools is like driver for the virtual hardware, it must be installed
    what mwecomputers mentioned is true, overall performance has been improved with vmware server 2
    If you follow the upgrade path properly, upgrade the virtual hardware to version 7 & then upgrade the vmware tools, there's no reason why your old VM will suffer on vmware server 2
    LVL 4

    Expert Comment

    Are you using the standard version of SCO 5.0.7 or the new 5.0.7V
    LVL 21

    Expert Comment

    Your server seems to be more than capable of running ESXi ... if you all you want to do is run 1 VM on it ... I would strongly recommend ESXi over CentOS
    But what nobody seems to have noticed is this:
    What you must also understand is that your older servers, even though old, are running 15K SCSI drives. Your new server now has 7200 SATA drives. SATA is nowhere near fast enough as good old SCSI. 7200RPM drives are also spinning 50% slower than your old drives! The new equivalent SCSI equivalent are SAS drives. This disparity between the speed of the old drives and the new drives are more than enough to cause the slow down in performance that you are experiencing.
    I also think the reason your test ran faster on your DL380G5 is that it has SAS drives!
    This is where your biggest issue is!
    My 2c from doing lots of SAN testing across SAS, SATA drives!

    Accepted Solution


    Here is an update: I moved the SCO VM from the old Linux servers (15K RPM SCSI) to the new Linux server (7200 RPM SATA), since my benchmark showed the VM to run about 5 times faster on new server, despite the faster disks in the old server.  Still running VMWare Server 1.0.10.  The performance is now acceptable.

    I am still considering moving the SCO VM to our ESXi server, since it is a lot more powerful and ESXi is much faster than VMWare Server.  The only issue with this is that I only have one ESXi server, and I need a stand-by backup server for the SCO VMs (in case the live server crashes and cannot be brought back up in a timely fashion.  Since there is no way to simply copy the VM files from ESXi to VMWare server, I would have to use the VMWare converter, which takes hours (and may not even work).

    With VMWare Server, I have a script that simply suspends the VM on the live server, copies the files to the backup server and starts the VM again.  I do not see a way of doing this if I use ESXi, unless I get a second server with ESXi (which is not in the budget at the moment).

    However, I tried upgrade our ESXi server from 3.5 to 4.0 so that I can convert the VM and see how it runs on ESXi. I need ESX4, since the SCO VM is using an IDE disk controller (despite the disks being SCSI), and ESXi 3.5 does not support IDE.

    The upgrade failed with "installation aborted Error: Failed to deactivate dump partition" (I posed a separate question on this, which is still unresolved).  After this, when I restarted this server, it will no longer boot ("Failed to find HD boot partition").  A quick Googling found this issue in one of the FAQs, but I have not yet had time to look into it (but chances are that it was caused by the failed update attempt, since nothing else has been done with that server recently).  

    This incident underscores the importance of having a stand-by backup server or similar, which is synchronized with the live server at least nightly.  However, I might still move the SCO VM to ESXi once I get it up and running again, and just use RSync or similar to synchronize only the data inside the SCO VM on ESXi to the data inside a backup SCO VM on VMWare server.

    If I am missing something in my ramblings above, input is welcome.


    Ps. To answer one of the posts above: I am using Open Server 5.0.7 - not 5.0.7V.
    LVL 29

    Expert Comment

    by:Michael W
    Can this issue be closed out or does it still exist and need to be worked/clarified upon?

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