HP Virtual SAN Appliance (formerly LeftHand)

Its been a while since I wrote something, so I feel obligated to make a post geek related. A few months back I started looking into a way to offer some sort of high availability to our sites while decreasing the cost. Previously we would cluster up the SQL server and hope for the best. Obviously this is not great, and still quite expensive to only have 2 servers with any level of redundancy.

When I started looking at shared storage and VMWare solutions, I came into the same issues. There are not many choices in the realm shared storage that is fast and offers redundancy without using multiple units. That is when I started looking at the VSA software. If you have not seen this before, it is pretty cool. Essentially you take the DAS disk from multiple ESX servers and create RAID sets across the servers.

This presents a few pros and cons depending on how you design this, and what you are going to use it for. If you use at least 3 servers and RAID 10 sets to provision your LUNs, then you can lose one of your 3 ESX hosts and you will stay running. With vMotion from VMWare, any servers on that host will fire back up on one of the other hosts. You need to be careful that there are enough resources to lose 1 server. Another positive to this design is that you are able to expand out by adding disk shelves, additional servers, or even moving to an HP SAN later (like a p2000). Expanding out more disk, or moving storage around is simple with the VSA interface. Very impressed so far.

There is a downside to all of this. There is a ton of disk overhead to contend with. You do have choices, but the most popular appears to be RAID 5 sets for the raw disk, and then RAID 10 on top of that. Its pretty obvious that this will slow things down a little bit when it comes to disk. You can combat this by using fast disk, but there is only so much you can do. If you are using very high I/O applications, I would not recommend this solution.

We are lucky that the applications we use for our remote sites do not have really high disk I/O. This solution allows us to offer highly available applications and makes it easy to expand as their needs change.

Enable SNMP in ESXi 4.1 or ESX 4.0

There are many reasons you will have for wanting to enable SNMP on your ESX hosts, and a whole slew of applications out there to monitor your environment. I have been playing with the Orion APM module lately, and it is not too bad. The newest version now has some support for virtual hosts, so I figured I would add those to see what kind of goodies they have. These directions may work for other versions of ESX, but these are the only 2 I currently have in my environment and I know this will work for those.

First off, you will need to download the VMware vSphere CLI. This is different from the VMware powershell installation and will allow you to make a run quite a few common commands remotely against your ESX environment from Windows or Linux systems.

Once this is installed, we need to configure your community, string and port to be used. If you are using Windows, you need to launch the CLI and change the directory to the bin folder. Here is the syntax to configure:

vicfg-snmp.pl --server  -c  -p 161 -t @161/

You will be prompted for the root username and password for the ESX host.

Next we will need to enable it:

vicfg-snmp.pl --server  -E

Again you will be prompted for the root username and password.

Now you should be able to add the host to Orion, or whatever your monitoring application of choice is.