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Posts Tagged ‘vSphere’

vscsiStats is definitely a cool tool. Now that the 2D barrier was broken in vscsiStats into the third dimension: Surface charts! it is time to move on to the next level: Multiple VMs fighting for IOPS!

Update: Build your own 3D graphs! Check out vscsiStats 3D surface graph part 3: Build your own!

I figured the vscsiStats would be most interesting in a use case where two VMs are battling for IOPS from the same RAID set. A single VM would have to force I/O on a RAID set. Wouldn’t it be cool to start a second VM on the same RAID set later on and to see what happens in the 3D world? In this blogpost I’m going to do just that!

TO THE LAB!

The setup is simple: Take a LUN on a RAID5 array of (4+1) SATA72K spindles, take two (Windows 2003 server) VMs which have a datadisk on this LUN. Now install iometer on both VMs. These two instances of iometer will be used to make both VMs fight for IOPS.

The iometer load is varied between measurements, but globally it emulates a server load (random 4K reads, random 4K writes, some sequential 64K reads).

First only a single VM runs the iometer load. At 1/3rd of the sample-run, the second VM is started to produce the same IO pattern. At 2/3rd, the first VM stops its IO pattern load. This results in the following graph:

Read the rest of this entry »

How could I ever have missed it… vscsiStats. A great tool within vSphere which enables you to see VM disk statistics. And not only latency and number of IOPs… But actually very cool stuff like blocksizes, seekdistances and so on! This information in not to be found in esxtop or vCenter performance graphs… So we have to rely on once more on the console…

UPDATE: Available now: vscsiStats in 3D part 2: VMs fighting over IOPS !
UPDATE2: Build your own 3D graphs! Check out vscsiStats 3D surface graph part 3: Build your own! Read the rest of this entry »

Now that I am busy setting up UDA 2.0 (beta14) for a customer to be able to reinstall their 50+ VMware servers, I stumbled upon this message. The install would hang briefly, then proceed to a “press any key to reboot” prompt. Not too promising…

After searching the internet I found a lot of blog entries on exactly this error. I could not find any useful hints or tips that would solve my problem; I have been checking the disk layout over and over again, to make sure no mistakes were made there. I was starting to pull my hair out, because it did work previously.

Then I started thinking; the customer in question has multiple PxE servers in the same network, and special DHCP entries were created for all vmnic0 MAC addresses, so that option 66 and 67 could be set to point to the UDA appliance. I think their DHCP server denies DHCP to any MAC address unknown to it, because right before the “press any key to reboot” I saw something passing in the line of “unable to obtain a dynamic address”. I figured in the initial setup, the kickstart part tries to get a DHCP address using the Service Console virtual NIC (with a different MAC address each time you reinstall). So I tried to alter the “Kernel option command-line” from this:

ks=http://[UDA_IPADDR]/kickstart/[TEMPLATE]/[SUBTEMPLATE].cfg initrd=initrd.[OS].[FLAVOR] mem=512M

VMware just released vSphere 4.0 update 2. Not much new stuff, except improvements in Guest Operating Systems improvements:

Guest Operating System Customization Improvements: vCenter Server now supports customization of the following guest operating systems:

• Windows XP Professional SP2 (x64) serviced by Windows Server 2003 SP2
• SLES 11 (x32 and x64)
• SLES 10 SP3 (x32 and x64)
• RHEL 5.5 Server Platform (x32 and x64)
• RHEL 5.4 Server Platform (x32 and x64)
• RHEL 4.8 Server Platform (x32 and 64)
• Debian 5.0 (x32 and x64)
• Debian 5.0 R1 (x32 and x64)
• Debian 5.0 R2 (x32 and x64)

Also a lot of resolved issues; which is always nice to have!