From: Brehl, Blake (Blake.Brehl@anritsu.com)
Date: Tue Oct 29 2002 - 13:02:04 EST
Original post below. Thank you's to responses from Andy Wagg and Dennis
Sylvester. Also received 2 reply's from a database list, and contacted
Compaq Support. All pointed in the direction of being aggressive in
lowering the tcp_keepalive time, setting at 5 or even 2 minutes for the
entire cycle. Compaq Support reflected they have Database customers which
cycle under a minute, leveraging a keepcnt of 2 or 1. The concern is other
applications, and native services using TCP. FTP, RCP and NFS come to mind.
I've set the following 2 minute cycle on the development box, will run it
for a week, then push it to live.
tcp_keepidle 60 seconds (120 ticks)
tcp_keepcnt 4
tcp_keepintvl 15 seconds (30 ticks)
Best Regards, Blake
> Andy Wagg:
>Our systems are running with the keep alives set so a connection is
>dropped after a maximum of two minutes. I have never noticed any adverse
effects.
> Dennis Sylvester:
>I don't know what DB vendor you are referring to but
>tcp_keepidle at 600 (five minutes) has solved any problems we
>have had in the past and not adversely affected Oracle or
>Informix and worked well on all systems.
>I have made these changes across hundreds of servers from
>4100's to GS320's and from 4.x to 5.1A without ever changing
>anything except tcp_keepidle, and never having to go below 600 ticks.
> Tom Bascom:
>I've gone as low as 5 minutes. No problems. Ever.
> Geoff Crawford
> I don't see much wrong with 5 min. That's about as much patience I could
possibly muster in
> today's fairly reasonable networks.
>-----Original Message-----
>From: Brehl, Blake
>Sent: Monday, October 28, 2002 11:20 AM
>To: Tru64 Mailing List (tru64-unix-managers@ornl.gov)
>Subject: enabling tcp keepalive, 1st time
>
>
>We're enabling tcp_keepalive (tcp_keepalive_default = 1) for
>the first time, to address telnet clients that drop without
>returning a signal 1. This has been compounded by remote
>clients on VPN on LINKSYS Cable modems.
>
>I'm trying to determine how aggressive I can make the
>settings. The Database vendor has recommended minimums, but
>doesn't qualify why. I've tried more aggressive setting on a
>development box and haven't seen any problems.
>
> Factory db vendor
>Development
> Default minimums Box try
>
>TCP_KEEPIDLE 2 hours 15 minutes 3 minutes
>TCP_KEEPINTVL 75 seconds 60 seconds
>15 seconds
>TCP_KEEPCNT 8 6 8
>
>Total time
>till disconnect 2 hr 10 minutes 21 minutes 5 minutes
>
>It would be wonderful if these drops could be cleaned up in
>minutes. I'm wondering how aggressive I can set this? Please
>share your settings and any warnings.
>
>Tru64UNIX 5.1 pk1, and 5.1A pk1
>
>
>Best Regards,
>
>Blake Brehl
>Sr. Database Administrator
>Anritsu Company United States
>Morgan Hill, CA
>
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