Seemingly odd disc i/o behaviour, need help to diagnose

[Mark Kirkwood]

Oren Baum wrote:
> 
> Configuration:
> 
> FreeBSD 4.4-RELEASE
> apache+mod_ssl-1.3.22+2.8.5_1
> mysql-server-3.23.42
> Hard Drive (dual ATA disks, no RAID) on a Dell P4 PowerEDGE server
> 
> We had many speed and timeout issues so we recompiled the kernel with 
> maxusers=128 instead of the previous 32 and moved the hard drives into a new 
> P4 2.8Ghz PowerEdge Case.
> 

What model number Poweredge ? (so we can examine specifications if need 
be). The amount and type of RAM would be good to know as well.

> atapci0: <Generic PCI ATA controller> port 0xffa0-0xffaf,0x374-0x377,0x170-
> 0x177,0x3f4-0x3f7,0x1f0-0x1f7 irq 11 at device 31.1 on pci0
> ata0: at 0x1f0 irq 14 on atapci0
> atapci1: <Generic PCI ATA controller> port 0xfea0-0xfeaf,0xfe30-0xfe33,0xfe20-
> 0xfe27,0xfe10-0xfe13,0xfe00-0xfe07 mem 0xdff3fc00-0xdff3ffff irq 5 at device 
> 31.2 on pci0
> ata2: at 0xfe00 on atapci1
> ata3: at 0xfe20 on atapci1
> 

FreeBSD 4.4 is detecting a 'Generic PCI ATA Controller', which may mean 
the capabilities are very dumped down (and performance is poor) - as no 
doubt other posters will mention, let me suggest 4.10 or 4.11 for better 
HW detection :-)

> If we run pine on a large mailbox or any other disk i/o intensive task, all 
> other processes in motion seem to stall until the disk i/o is complete.
> This manifests itself in timeouts on webpages that require DB data, IMAP 
> timeouts for other mail accounts, and even odd console/shell behaviour.
>

An additional possibility is that your old hard drives are becoming worn 
out. It is probably worth buying 2 fast new ones (maybe SATA if your 
Dell supports it - I suspect you will *need* be off 4.4 before trying 
this tho!).

regards

Mark