Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My server is experiencing very high load average spikes (>10, sometimes even >20) every few minutes.

top shows that CPU isn't in usage but is waiting for I/O operations:

top - 17:42:28 up 8 days,  8:10,  1 user,  load average: 9.01, 10.16, 6.54
Cpu0  :  0.0%us,  0.0%sy,  0.0%ni,  0.0%id,100.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu1  :  0.0%us,  0.0%sy,  0.0%ni,  0.0%id,100.0%wa,  0.0%hi,  0.0%si,  0.0%st

dmesg shows this output over and over again (I don't understand what it means):

ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2
ata2.00: BMDMA stat 0x26
ata2.00: cmd ca/00:08:74:c4:24/00:00:00:00:00/ef tag 0 dma 4096 out
         res 51/84:01:7b:c4:24/84:00:10:00:00/ef Emask 0x30 (host bus error)
ata2.00: status: { DRDY ERR }
ata2.00: error: { ICRC ABRT }
ata2: soft resetting link
ata2.00: configured for UDMA/33
ata2: EH complete
sd 3:0:0:0: [sdb] 625142448 512-byte hardware sectors (320073 MB)
sd 3:0:0:0: [sdb] Write Protect is off
sd 3:0:0:0: [sdb] Mode Sense: 00 3a 00 00
sd 3:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Any ideas?

There is FreeRADIUS running on server and I am suspecting that either RADIUS either network adapter might be causing the problem. During some spikes tcpdump showed increased number of RADIUS packages being sent/received (but I'm talking about tens of packages per minute, not thousands of them).

When I stop RADIUS situation gets better, but there are still periodic load avg spikes (more tolerable though).

Does anybody have an idea what might be causing this behavior, and how I can determine for sure is it RADIUS, network adapter, or something else?


share|improve this question
What distribution are you using? – Mark Johnson Dec 9 '11 at 17:51
Slackware 12.1.0 – celicni Dec 9 '11 at 18:01
up vote 3 down vote accepted

No, this is either one disk or a disk controller dying. This has nothing to do with the software you're running or the network adapter.

If you're not already doing backups - make one NOW and start to look for replacement hardware.

share|improve this answer
There are two disks in RAID1 and both disks have been changed recently (because of failure). They seem to have passed the SMART test. Raw_Read_Error_Rate is in "pre-fail", however I've tested it on some other servers and it was in "pre-fail" as well, so I'm not sure what it means. – celicni Dec 9 '11 at 18:12
It turned out /dev/sdb was failing and that caused the problem. Thanks for the answer! – celicni Dec 14 '11 at 13:36

An almost identical question like this has been posted on SU

Before you reboot or tinker with settings - perform backup (And parity check it!) ASAP.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.