IO impacting systems responsiveness

[Brian A Seklecki (Mobile)]

> written and deleted from local disk quickly) we can't even log in to
> the
> machine - and our monitoring system get's all freaked out and we get
> lots of pages, etc... FYI this is two disks with hardware raid 1.

If you were running FreeBSD, i would tell you to check your interrupt
counts to see if your Ethernet Card or HBA to blame:

$ vmstat -i
interrupt                          total       rate
irq0: clk                     1585207335        269
irq1: atkbd0                          30          0
irq4: sio0                             3          0
irq8: rtc                      752559800        127
irq10: bge0 uhci1+             787961312        134
irq11: uhci0 ehci+              10981712          1
irq14: ata0                           59          0
Total                         3136710251        533

As you can see from this (PE850), the crappy Broadcom cards cause a lot
of overhead under high loads.  The ICH7 does not.

~BAS