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Is it a new miss election?? Well, after doing more than a little testing I figured out I may be MISSing something… So unfortunately it is not about beautiful women, but yet another technical deepdive. This time into misalignment. Theoretically it is SO easy to point out what the problem is (see Throughput part 3: Data alignment. For this new blog entry I had my mind set on showing the differences between misalignment and alignment in the lab… However this proves to be much MUCH harder than anticipated…

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New and improved in vSphere: Datastore alarms. Very nice to have, but some of these alarms are so generic, that datastores are simply always in an alarmed state. Errors like “non-VI workload detected” on your ISO LUN, “Datastore usage on disk” and so on. Here’s how to loose these errors on certain stores while enforcing them on others.

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Amongst many of the optimizations for virtual desktops, it is always stated that the LSI Logic virtual disk controller is faster/more efficient than the BusLogic controller. So is this really true in vSphere 4.1 environments?

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Today I got my hands on the new PHD Virtual Backup Appliance – version 5.1-ER. Following in the footsteps of its XenServer brother, this new version uses a single VBA (versus the previous versions where multiple VBA’s were used). Best of all: ESXi support at last!

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Some time ago I posted Surviving total SAN failure which I had tested on ESX 3.5 at the time. A recent commenter had trouble getting this to work on a vSphere 4.0 environment. So I set out to test this once more on my trusty vSphere 4.1 environment.

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In this post: Throughput part 2: RAID types and segment sizes I wrote that a RAID5 setup can potentially perform better in a heavy-write environment over RAID10, if tunes right. While theoretically this might be true, I have some important addendum’s to this statement that vote against RAID5 which I’d like to share.

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This year on December 10th I’ll be visiting the Dutch VMUG day 2010 in Nieuwegein, the Netherlands. My first time as a blogger! I will be visiting this event for the fourth time, and it has been a great event every single year.

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:

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A collegue of mine, John Grinwis, pointed out a bug within a combination of ESXi, host profiles and an EMC CLARiiON: At some point the ESXi nodes swap their VMkernel ports and the CLARiiON then proceeds to register the wrong network as the management network

UPDATE: There now is a workaround available. Please visit Workaround: ESXi and EMC CLARiiON registration issue

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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 »