Daz’s bits and bobs

Most of the time your HA issues are going to be DNS related. So ensure that your vcenter can ping all your hosts by FQDN without issue.  In some cases though a stubborn server may not want to play the game even when everything is configured properly.

This method is considered a “last effort” as you’ll need to run some CLI commands on the ESX box. But i have found it useful in a few situations.

This page has a great write up on which files HA uses and how to temporary stop the HA service. http://itknowledgeexchange.techtarget.com/virtualization-pro/vmware-ha-failure-got-you-down/

Remember to get to the console on ESXi you logon to the console press Alt-F1 then type “unsupported” (note: you cannot see what you are typing), then enter the root password.

The main bits are as follows;

Stop the HA service

service vmware-aam stop

Check that HA has stopped (if not then use kill command to kill them)

ps ax | grep aam | grep -v grep

Move the current HA config files to a backup directory (before restarting HA)

cd /etc/opt/vmware/aam

mkdir .old

mv * .old

mv .[a-z]* .old

Then back to your vcenter and select Reconfigure for VMware HA on the effected host. Fingers crossed that it starts up and reconfigures without any issues.

This bug has hit me. Looks like users with roles like vm user / power user cannot send “ctrl-alt-del” via the console even though they have the correct permissions. Our users cannot use ctrl-alt-ins as they are connected via RDP to a machine that has the console installed.

Found this : http://communities.vmware.com/thread/220683;jsessionid=480C8A2C9B9EACA9FF2BB4E1BECA2D53?start=15&tstart=0

Looks like its a known bug and will be fixed in the upcoming VC4.0 update 1 sometime Q3 2009 :(

Luckily vSphere was setup in our pre-production environment - the machines i have running in production are still 3.5 with VC2.5.

Since im using ZFS as storage via NFS for my some of my vmware environments i need to ensure that latency on my disk is reduced where ever possible.

There is alot of talk about ZFS compression being “faster” than a non-compressed pool due to less physical data being pulled off the drives. This of course depends on the system powering ZFS, but i wanted to run some tests specifically on latency. Throughput is fine in some situations, but latency is a killer when it comes to lots of small reads and writes (in the case of hosting virtual machines)

I recently completed some basic tests focusing on the differences in latency when ZFS compression (lzjb) is enabled or disabled. IOMeter was my tool of choice and i hit my ZFS box via a mapped drive.

I’m not concerned with the actual figures, but the difference between the figures

I have run the test multiple times (to eliminate caching as a factor) and can validate that compression (on my system anyhow) increases latency

Basic Results from a “All in one” test suite… (similar results across all my tests)

ZFS uncompressed:

IOps : 2376.68
Read MBps : 15.14
Write MBps : 15.36
Average Response Time : 0.42
Average Read Response Time : 0.42
Average Write Response Time : 0.43
Average Transaction Time : 0.42

ZFS compressed: (lzjb)

IOps : 1901.82
Read MBps : 12.09
Write MBps : 12.28
Average Response Time : 0.53
Average Read Response Time : 0.44
Average Write Response Time : 0.61
Average Transaction Time : 0.53

As you can see from the results, the AWRT especially is much higher due to compression. I wouldn’t recommend using zfs compression where latency is a large factor (virtual machines)

Note: Under all the tests performed the CPU (dual core) on the zfs box was never 100% – eliminating that as a bottleneck.

This is something i do in the lab so all of my vm’s are able to access iso’s etc (very handy for quick builds). Quite handy doing it through windows since its easiey enough to setup a windows network share to the same location and update various files via that.

This site has some good clear instructions : http://vmetc.com/2008/02/19/create-a-nfs-share-for-vm-iso-files-with-windows-2003-server-r2/

1. On the Windows 2003 Server make sure “Microsoft Services for NFS” in installed. If not you need to add it under Add/Remove Programs, Windows
   Components, Other Network File and Print Services
2. Next go to folder you want to share and right-click on it and select Properties
3. Click on the NFS Sharing tab and select “Share this Folder”
4. Enter a Share Name, check “Anonymous Access” and make sure the UID and GID are both -2
5. In VirtualCenter, select your ESX server and click the “Configuration” tab and then select “Storage”
6. Click on “Add Storage” and select “Network File System” as the storage type
7. Enter the Windows Server name, the folder (share) name and a descriptive Datastore Name
8. Done. Now you can map CD iso’s to your various vm’s.