Quite the backup solution! You didn't happen to ask him why he chose a
RAID 1 over four disks did you? Is the read performance on a RAID 1
directly proportional to the number of disks in the array? I know read
performance doubles (in theory) when mirroring two disks. Of course, this
person was clearly not concerned with performance if they were using USB
drives. What solution did you come up with to their problem?
I'm using md devices through the mdadm utility.
I never experience the timeout issue on the Nvidia controller. I thought
that it may have something to do with native command queuing, but a) it's
accomplished on a hardware level (like out of order execution), and b) the
disks worked fine on the Nvidia controller. Okay, so there's a hole in my
logic... but when the new disks arrive (NCQ enabled) I'll be able to tell
for sure if NCQ had anything to do with this issue.
Nice controller! The nForce 4 Pro chipset uses the PCIe bus to provide 4
channels of SATA. I'm not particularly impressed with the performance yet
(perhaps those bastards at Nvidia should release a driver), but it does
work. Do you have any write/read benchmarks to show off? I'd like to
compare them to my new lab machines (apples to oranges, but what the
hell)? What model did you get, and how much did it cost?
- Sebastian
On Mon, 22 Aug 2005, Brandon Mitchell wrote:
Hey Sebastian:
Actually, I experienced a (somewhat) related problem, today. I took a call
through the usual inter-office 'hot potato' routine, though this one was for
the recordbooks.
The guy on the other end of the line was curious why _his_ RAID array was not
being detected. This array was of the md-based variety (as yours probably
is), except that he had created a RAID 1 array using 4 USB harddisks, with a
hot spare! Following a recent power bump, all data on this array was rendered
unusable (no UPS, either). The kicker was that he was using this half-baked
scheme as his lone backup solution on a series of _production_ Ubuntu
servers.
Well, enough of the braindamaged user stories. Were you able to replicate the
timing issue on the nForce SATA controller. I have had rather poor experience
with SiI controllers, though I recently had an excuse to splurge for one of
these: http://www.areca.com.tw/products/html/pciE-sata.htm
I have been _extremely_ happy with its performance in FreeBSD. Good luck!
---
Brandon Mitchell
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