iSCSI Moves Toward Standard

EyesWideOpen writes "The iSCSI technology, which allows computers to connect to hard drives over a network connection such as a company Ethernet network or the Internet, requires only minor changes before the Internet Engineering Task Force endorses it as a formal version 1.0 standard. A final round of comments has been completed on the technology according to the Storage Networking Industry Association, the subgroup that led the creation of the iSCSI, and as a result companies now can start building iSCSI products."

Comments

iSCSI not ready for prime time

[IGnatius T Foobar]

I work at a mid size hosting facility, and we've done quite a bit of experimentation with iSCSI. In my opition it's not ready yet. Either that or it's just a bad idea, full stop.

We do quite a bit with our SAN -- there are a coupla IBM 2105 ESS ("Shark") boxen in the back of the data center with many terabytes of disk online. It's all about Fibre Channel. At least as fast as SCSI, effectively faster when you have all sorts of cache running on the storage side, and you have the flexibility to define exactly how much disk goes to what server, and you can add more dynamically without a power down, etc.

Unfortunately, Fibre Channel is expensive. It requires expensive host bus adapters and even more expensive switches. And of course it runs over fiber optic cable, which isn't exactly penny kit. So the industry decided to try running it over Ethernet.

Now there are iSCSI-to-Fibre gateways, such as Cisco's 5420 Storage Router (which we've evaluated), but there are just problems in general with running block level storage over a TCP/IP network...

• For one thing, it's only as reliable as your network. If you have a network problem such as a down switch/hub etc, you lose your disks immediately.
• Unlike SCSI and Fibre Channel, you can't boot from an iSCSI volume. This is because your operating system has to be loaded, and your TCP/IP stack initialized, before you can load the iSCSI driver.
• Most operating systems want to load their storage drivers before they load their networking drivers. Doing it the other way around challenges all sorts of assumptions made by various system software out there. Sounds trivial, but again, we've evaluated it, and the result ain't pretty.
• By putting block level storage on your LAN, you've increased the capacity requirements by several orders of magnitude. To get any reasonable performance you're going to need Gigabit Ethernet everywhere -- and if you're going to make that kind of investment, you might as well be doing Fibre Channel.

That's why our iSCSI stuff is just sitting around doing nothing right now.

The only place I can see iSCSI being used at this time is for really temporary quick-and-dirty setups, such as a programmer needing another 100 GB online for a one-week project. But even then, NAS seems like a better idea.