[plug] server failing with bizarre disk errors

[Craig Ringer]

> One thing that can cause drives to behave erratically is not enough power, what size PSU is in the machine?

500W but you know how those things are. I'm installing a new Enermax 
550W (honestly 550W capable not the usual BS) tonight.

> I'm assuming there are good fans cooling off the drives.

Yeah. My home box doesn't have drive bay cooling and that's the cause of 
/its/ problems I suspect. Very different to this though.

> Another issue to look at is using drives with small cache, they are not designed for servers but for workstations.  

8mb of cache is not overly small.

> When I did my training with Compaq the one thing they stressed to us was the proper use of HDD in servers.  They stressed in a production environment NEVER under any circumstances use an IDE drive.  The data will create a bottleneck effect.  This is due to a server "serves" multiple requests and a workstation only does "requests" and that is done one-at-a-time.  For this reason a SCSI system should always be used in a server. You may want to consider this.  Yes, I know most would argue that the EIDE drives are closing in on the EIDE drives, but it's not the speed that is the issue, it's the number of instructions that the processor is precessing to the drives that is causing the issue.  Workstations IDE drives can only do so many per cycle.  Whereas the server has to do a whole lot more in the same time.

(a) lots of workstations need multiple accesses in progress for decent 
interactivity
(b) Some modern ATA drives and chipsets support TCQ, allowing multiple 
in-flight commands SCSI style.
(c) SATA has solved the issue anyway.

While I'm sure Compaq had some good technical reasons, I wouldn't be 
surprised if they also wanted to sell more SCSI disks in their servers ;-)

I do see your point though - the HDD manufacturers tune the drive 
firmware for "desktop" access patterns - but that is not a reason for 
crashes and total access failures, just poor performance. The demands on 
this machine are significant, but nothing like a video editing 
workstation or even a personal database.

Craig Ringer