RAID prices declining, performance increasing?

By Steve Antonoff, ITworld.com |  Storage

I had a conversation recently with Eric Herzog, vice president of marketing at
Mylex, that centered on three new RAID cards the company will be announcing this month.
But before we get to that conversation, let me relate some experiences.

I've been using RAID (redundant array of independent disks) configurations for five
years or so. Usually, full mirroring isn't an option, either due to cost or space
restraints, so I usually use RAID-5. For the most part, I've had very good experiences.
RAID-5 does protect data, allowing a system to continue to operate when a single drive
fails. I have had some less than perfect results, though.

On various systems, with different brand RAID controllers, I've occasionally had a
disk drop off-line. Without RAID, the server would be in serious trouble and require
immediate attention. With RAID-5, the server continues (usually with a fairly annoying
BEEP-BEEP-BEEP drawing attention to the situation) until the server can be properly
shut down (preferably after a full backup, just in case). In more than 90 percent of
those occurrences, nothing is wrong with the drive. After a power down cycle, it
recovers from whatever anomaly it experienced and resumes work, operating for many
months or years. The RAID controller must be instructed to rebuild the array. That is
not a problem unless the RAID controller support software in question is DOS-based and
the server must be booted from a DOS disk and kept off-line until the rebuild is
complete. Newer software will allow common operating systems to operate while the array
is reconstructed. There's a trade-off here: risk versus downtime. You have no
redundancy until the rebuild is complete, so if a second disk fails, you're hosed.

OK, back to Eric and Mylex.

Mylex is driving down the price of RAID controllers -- the new Mylex controllers
will start at $499, list price. Those are single-channel, 160 MB/sec, wide controllers,
capable of handling up to 15 drives. Two of the controllers are standard PCI form
factor, designed for a normal, full-size server. One of those comes with 32 MB of
cache, the other with 64 MB. Eric promised to get me one of the 32 MB cards to play
with, and I'm looking forward to receiving it. And, of course, I'll let you know the
results.

The third card is a new form factor being pushed by Intel. The form factor is
supposed to allow more system boards to be installed in a smaller space in a rack.
Think of an application service provider (ASP), a web hosting site or a co-location
facility: hundreds of Intel-based systems and the closer together the boards can be
stuffed, the less floor space you need. One ISP in Atlanta told me recently that there
is no co-location space left anywhere in that city, so they're building a new facility
to accommodate the growth. Having more computers in less space is another
alternative.

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