CentOS 5/6 - random temporary freezes

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drk
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Re: CentOS 5/6 - random temporary freezes

Post by drk » 2014/04/17 02:53:40

hpet enabled in bios?

Do any users notice when it "freezes" - ie keyboard input interrupted?

I'd start stripping out any hardware/peripherals installed and/or plugged in, disable cpu frequency apps etc and see if any of them are causing trouble.

drk
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Re: CentOS 5/6 - random temporary freezes

Post by drk » 2014/04/17 03:15:53

zinok wrote:Last few months I noticed some strange issue when it takes 500-700 ms to answer packet, while usually it takes 20 ms.
Presumably they were fine before? Was something added to your LAN that causes momentary anarchy?

I've seen a badly crimped CAT5 cable cause everything on a client's LAN to grind to a halt but the delays were longer than 500-700ms. Doesn't hurt to ask if some recently "cleaned up" their computer area and tightly bundled all their cables to make it all neat ;)

zinok
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Re: CentOS 5/6 - random temporary freezes

Post by zinok » 2014/04/17 10:30:48

drk wrote:
zinok wrote:Last few months I noticed some strange issue when it takes 500-700 ms to answer packet, while usually it takes 20 ms.
Presumably they were fine before? Was something added to your LAN that causes momentary anarchy?

I've seen a badly crimped CAT5 cable cause everything on a client's LAN to grind to a halt but the delays were longer than 500-700ms. Doesn't hurt to ask if some recently "cleaned up" their computer area and tightly bundled all their cables to make it all neat ;)
Doesn't seem to be the case, problem is observed on two different server in two totally different locations.

zinok
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Re: CentOS 5/6 - random temporary freezes

Post by zinok » 2014/04/17 10:31:42

drk wrote:hpet enabled in bios?

Do any users notice when it "freezes" - ie keyboard input interrupted?

I'd start stripping out any hardware/peripherals installed and/or plugged in, disable cpu frequency apps etc and see if any of them are causing trouble.
Will check hpet, thanks.

As for keybord / mouse - server is accessed via SSH only. So almost impossible to check it.

drk
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Re: CentOS 5/6 - random temporary freezes

Post by drk » 2014/04/17 19:13:11

zinok wrote:Doesn't seem to be the case, problem is observed on two different server in two totally different locations.
It's not something crazy like the system was idle and spun down disk(s) and the delay is the disk(s) spinning back up?

Or even smartd polling a sleeping disk? Something checking the cd/dvd drive?
Last edited by drk on 2014/04/17 19:20:22, edited 1 time in total.

drk
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Re: CentOS 5/6 - random temporary freezes

Post by drk » 2014/04/17 19:18:38

zinok wrote:As for keybord / mouse - server is accessed via SSH only. So almost impossible to check it.
How about the cpu frequency minders? I asked once and mentioned it another time but you haven't answered :)

What is the full hardware specs of each server?

drk
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Re: CentOS 5/6 - random temporary freezes

Post by drk » 2014/04/17 19:32:07

zinok wrote:Write is writing to just a local file. Unfortunately the problem is not only on writes. Here is two more examples today:

13:08:12.663623 stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2309, ...}) = 0
13:08:12.926411 write(3, "[2014-04-15 13:08:12,663] WARNING WORKER 80 - [pkt#3395853/ACCT-START] Time between ...

300 ms on just stat /etc/localtime

and
13:08:13.347081 stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2309, ...}) = 0
13:08:13.530962 poll([{fd=18, events=POLLOUT}], 1, 3000) = 1 ([{fd=18, revents=POLLOUT}])

200 ms more...


It is not NTP time adjustment as seen on two separate servers and measured by tcpdump at both of them.
One other thing: Since you have these timestamped logs can you check if the delays are coming at a consistent time period - ie every 2 minutes or so?

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TrevorH
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Re: CentOS 5/6 - random temporary freezes

Post by TrevorH » 2014/04/17 19:43:47

I have an idea that's worth trying. As root, run this

Code: Select all

mount -o remount,commit=300 /
Repeat for all other ext[234] mounted filesystems. Retest and see.
The future appears to be RHEL or Debian. I think I'm going Debian.
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke

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