64-bit OES provides some options to highly available file serving. Now that we've split the non-file services out of the main 6-node cluster, all that cluster is doing is NCP and some trivial other things. What kinds of things could we do with this should we get a pile of money to do whatever we want?
Disclaimer: Due to the budget crisis, it is very possible we will not be able to replace the cluster nodes when they turn 5 years old. It may be easier to justify eating the greatly increased support expenses. Won't know until we try and replace them. This is a pure fantasy exercise as a result.
The stats of the 6-node cluster are impressive:
- 12 P4 cores, with an average of 3GHz per core (36GHz).
- A total of 24GB of RAM
- About 7TB of active data
The interesting thing is that you can get a similar server
- HP ProLiant DL580 (4 CPU sockets)
- 4x Quad Core Xeon E7330 Processors (2.40GHz per core, 38.4GHz total)
- 24 GB of RAM
- The usual trimmings
- Total cost: No more than $16,547 for us
With OES2 running in 64-bit mode, this monolithic server could handle what six 32-bit nodes are handling right now. The above is just a server that matches the stats of the existing cluster. If I were to really
replace the 6 node cluster with a single device I would make a few changes to the above. Such as moving to 32GB of RAM at minimum, and using a 2-socket server instead of a 4-socket server; 8 cores should
be plenty for a pure file-server this big.
A single server does have a few things to recommend it. By doing away with the virtual servers, all of the NCP volumes would be hosted on the same server. Right now each virtual-server/volume pair causes a new connection to each cluster node. Right now if I fail all the volumes to the same cluster node, that cluster node will legitimately have on the order of 15,000 concurrent connections. If I were to move all the volumes to a single server itself, the concurrent connection count would drop to only ~2500.
Doing that would also make one of the chief annoyances of the Vista Client for Novell much less annoying. Due to name cache expiration, if you don't look at Windows Explorer or that file dialog in the Vista client once every 10 minutes, it'll take a freaking-long time to open that window when you do. This is because the Vista client has to enumerate/resolve the addresses of each mapped drive. Because of our cluster, each user gets no less than 6 drive mappings to 6 different virtual servers. Since it takes Vista 30-60 seconds per NCP mapping to figure out the address (it has to try Windows resolution methods before going to Novell resolution methods, and unlike WinXP there is no way to reverse that order), this means a 3-5 minute pause before Windows Explorer opens.
By putting all of our volumes on the same server, it'd only pause 30-60 seconds. Still not great, but far better.
However, putting everything on a single server is not what you call "highly available". OES2 is a lot more stable now, but it still isn't to the legendary stability of NetWare 3. Heck, NetWare 6.5 isn't at that legendary stability either. Rebooting for patches takes everything
down for minutes at a time. Not viable.
With a server this beefy it is quite doable to do a cluster-in-a-box by way of Xen. Lay a base of SLES10-Sp2 on it, run the Xen kernel, and create four VMs for NCS cluster nodes. Give each 64-bit VM 7.75GB of RAM for file-caching, and bam! Cluster-in-a-box, and highly available.
However, this is a pure fantasy solution, so chances are real good that if we had the money we would use VMWare ESX instead XEN for the VM. The advantage to that is that we don't have to keep the VM/Host kernel versions in lock-step, which reduces downtime. There would be some performance degradation, and clock skew would be a problem, but at least uptime would be good; no need to perform a CLUSTER DOWN when updating kernels.
Best case, we'd have two physical boxes so we can patch the VM host without having to take every VM down.
But I still find it quite interesting that I could theoretically buy a single server with the same horsepower as the six servers driving our cluster right now.