|You've all read that 10GbaseT is on the way. It's true. Very soon, you will be able to plug standard RJ45 connectors (just like on your Mac Book Pro) into your 10Gb Ethernet cards and switches. You'll be able to run CAT6A cable 100m (assuming the runs are clean runs) and have tons and tons of bandwidth between servers and clients. Who needs Fibre Channel anymore?!|
But with the widespread migration to 10Gb, you may have a plumbing problem my friend.
Many years ago, I had the privilege of supporting three of the large animation studios in LA that were trying to use their new RAID5 arrays and run OC-3 and OC-12 right to their desktops. These two ATM standards were capable of 155Mbits and 622Mbits, respectively (this was before the days of Gigabit Ethernet). Everyone expected nirvana.
They didn't get nirvana. In fact, they found out right away that three clients ingesting media could very quickly "hang" their server. Within about 30 minutes it would slow to a crawl and sit there. They could not shut it down. Shutdown would hang. What was really happening? The machine had used all of its RAM collecting data and was unable to flush it quickly enough to their RAID. The machine was out of IO buffers and almost completely out of kernel memory. The "hang" was simply the machine doing everything it could to finish flushing all this unwritten data. We had to wait (and wait and wait).
Further, we discovered that with only three clients we could quickly start generating dropped packets. ATM had no flow control and so too many packets at once would result in dropped packets. Since the clients were very fast relative to the server, it didn't take more than a few to overwhelm it.
Similarly, as we all start to salivate over 10Gb to our Mac Books, iMacs and refrigerators, we should consider how we're going to deal with this massive plumbing problem.
First, you *will* need some form of back pressure. The server must be able to pause clients (and vice versa) or these new 300MB/sec flows are going to overwhelm all sorts of resources on the destination system.
Second, just because the network got faster, doesn't mean the disks did. In fact, now your users will have ample opportunity to do simple things like "drag and drop copies" that will use up a great deal of the resources on the server. A simple file copy over 10Gb at 300MB/sec bidirectional could overwhelm the real-time capabilities of a normal RAID. The solution lies in faster raids, SSDs and perhaps even 40Gb FCOE raids for the servers. (That's right, 40Gb FCOE raids)
So as you consider your 10Gb infrastructure upgrades, make sure you're working with an experienced vendor that knows about the pitfalls of "plumbing problems" and gets you setup with something that will work reliably and efficiently.