Thursday, March 27, 2008

VMware & PowerShell: Creating a PSdrive

I'm not the first to report it, but I wanted to share this here. My first reaction was: 'Cool!', and so is my second reaction... It is related to the fact that VMware released the beta of the PowerShell toolkit for VI.

Imagine you can browse your virtual infrastructure using a command line interface like this:

cd vi:
cd Folder01\DataCenter01\host\Web\LiveHost01

The original article can be found here. Have fun!

Monday, March 10, 2008

VMware VscsiStats: Measuring at the virtual SCSI level

I mentioned earlier that one of the presentations at VMworld Europe 2008 was about measuring at the level of the virtual SCSI adapter of a VM. A wealth of information is available when looking at this kind of information.

A tool is available on ESX 3.5 that creates histograms by default (and complete traces if wanted) is VscsiStats. As an option, one provides the vSCSI handle ID and the VM World ID. In order to get some statistics at all, one first needs to start the monitoring:

./vscsiStats -s

After some time, the relevant statistics can be fetched by issuing a command like:

./vscsiStats -i 8260 -w 1438 -p ioLength

This, for instance, yields an histogram of the size of IO pacakges sent to the virtual SCSI adapter (and thus to the storage array). To finalize the monitoring, it has to be stopped as well:

./vscsiStats -x

The result of the command above, in my test, was a graph like the one below:

This is a VM running Windows 2003. Remember this is a histogram, we put the measures points in 'buckets' according to their size and plot their relative frequency.

Remark that there is some IO with sizes 4095 bytes 8191 bytes. This is a sign that the file systems are not aligned properly. The fact that 4K sizes are the majority is nice, because VMFS is optimized for IO of 4KB.

Thursday, March 06, 2008

VMware: Virtual VCB Server/Proxy for iSCSI storage

(I know, I did not get past day 1 of VMworld Europe 2008, perhaps I will write some more about the other two days later this week...)

Something different now: It is known that VCB for VI 3.5 adds support for iSCSI devices, in itself this is not a big deal, but there is something really 'cool' about this: it means we can use a virtual server to act as a VCB proxy! This is a big step forward in my opinion.

How can this be done?
1. Install a virtual server
2. Connect the virtual network card of the server to the iSCSI network (either giving it the correct VLAN tag, or connecting it to the proper vSwitch).
3. Install a software intiator (e.g., the one you can download from the MS website. This step is pretty much the same as for a physical server.
4. Install & Configure VCB.
5. Configure the SAN to correctly present the LUNs to the backup proxy (based on the iqn).

Now, combine this with the possibility to add an iSCSI or NFS storage appliance to your virtual infrastructure, and you're ready to have a complete virtualized backup solution that is no longer tied to physical hardware.

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