Tag Archives: ZFS

Host based mirroring kills your storage network!!

System administrators are very inventive and lazy. I know, I used to be one of them. 🙂 Everything that can be done to make ones life easier is about to be scripted, configured, designed etc.  If you are responsible for an overall environment from Apps to servers to networks and storage you can make very informed decisions on how you want to set up each different aspect of your environment. The last time I had this opportunity was back in 1995. Since then I have not come across an environment where a single person/team was responsible for each technology aspect of the infrastructure. As environments grow these teams grow as well. Business decisions like splits, acquisitions, outsourcing etc etc have enormous impacts not only on the business itself but also on people who are now forced to work with other people/teams who may have different mind-sets, processes and procedures and even completely different technologies. In many such instances strange things will happen and result in a very unpredictable behaviour of compute, network and storage systems. Below I’ll give you such an example where decisions from a systems-level perspective results in massive problems on a storage network.

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Open Source Storage

Storage vendors are getting nervous. The time has come that SMB/SME level storage systems can be build from scratch with just servers, JBOD’s and some sort of connectivity.

Most notably SUN (or Oracle these days) has been very busy in this area. Most IP was already within SUN, Solaris source code has been made available, they have an excellent file-system (ZFS) which scales enormously and has a very rich feature set. Now extent that with Lustre ** and you’re steaming away. Growth is easily accomplished by adding nodes to the cluster which simultaneously increases the IO processing power as well as throughput.

But for me the absolute killer app is COMSTAR. This way you can create your own storage array with commodity hardware and make your HBA’s fibre channel targets. Present your LUNS and connect other systems to it via a fibre channel network. Better yet even iSCSI and FCOE are part of it now. Absolutely fabulous. These days there would be no reason to buy an expensive proprietary array but use the kit that you have. Ohh yes, talking about scalability, is 8 exabyte enough on one filesystem and over a couple of thousand nodes in a cluster. If you don’t have these requirements it works one a single server as well.

The only thing lacking is Mainframe support but since the majority of systems in data-centres have Windows or some sort of Unix farm anyway this can be an excellent candidate for large scale Open Source storage systems. Now that should make some vendors pretty nervous.


**ZFS is not yet supported in Luster clusters but on the roadmap for next year