[c-nsp] high CPU usage when coyping to flash

[James Slepicka (c-nsp)]

I previously ran into this issue w/ 4500 + Sup6E running 12.2(52)SG.  OSPF adjacencies would drop during file transfers.  TAC pointed me to CSCsw84727:

Writing to bootflash creates instabilities when using low timers
Symptom:
Writing to bootflash creates instabilities when using low timers (< 10 sec)

Conditions:
- low timers for control protocols are in use (e.g. HSRP, OSPF, BGP)
- supervisor/switch is one of: Sup6-E, Sup6L-E, 4900M, 4948-E

Workaround:
Avoid lengthy bootflash operations, like copying really large files in IOS.
Upgrade to 12.2(50)SG06, 12.2(53)SG02, 12.2(54)SG or above.

I'm running 12.2(54)SG now.  It's been a while, but I seem to recall still seeing high CPU utilization during flash operations, but OSPF would remain stable.

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jiri Prochazka
Sent: Sunday, February 26, 2012 2:43 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] high CPU usage when coyping to flash

Hi,

I've came to a strange behaviour on 4900M. When trying to copy a new IOS to flash, CPU utilization rises from usual 15% to 100%, even ssh stops answering, some ports are being disabled due to UDLD error, some were unbundled from etherchannels because of LACP-PDU not being generated.

The switch is just absolutely overloaded which cause a lot of issues. I did not want to believe simple 'copy tftp:// bootflash:' could cause this so I tried it once more, with the same result.


I am now trying to figure it in a lab, but it seems I am in a dead end.


I tried in on 4948E, 4900M, different IOSes (12.2(54)SG1, 15.0(2)SG1, 15.0(2)SG3).

I tried to use tftp, scp, http, all with the same result of 100% CPU usage.


I am not concerned about the high cpu usage itself, but I do absoltely do not understand why it effectively stops the rest of the switch to work properly..



Thank you for your advice.

-- 

Jiri Prochazka
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