High Load average no CPU utilization

adam fisher afisher at circlepix.com
Wed Mar 28 17:12:16 MDT 2007


Right now the box has a load average of 76 and I am able to cat files on the remote mounts and netstat -in doesn't report and nic errors.  I have munin monitoring this box and it hasn't reported any.  

I will try and increase the remote window size and force the mount rather than assume the defaults.

thanks for all your help,
Adam
----- Steve Alligood <steve at bluehost.com> wrote:
> If the other boxes are working fine with nfs, it probably isn't the 
> number of nfsd processes running (though you can change that in 
> /etc/sysconfig/nfs with the RPCNFSDCOUNT setting, default is 8).
> 
> Again, I would make sure it can actually get cat the files from the 
> fedora box during the higher load times, make sure the mount isn't 
> stale, that the network is performing correctly (forced NIC and 
> switchport rather than auto, check with netstat -in for interface 
> errors), and even make sure to force the nfs mount rather than assume
> 
> the defaults (BSD may default to a larger window, etc, etc).
> 
> None of these are certain, but places worth checking.
> 
> -Steve
> 
> adam fisher wrote:
> > This is the mount statement for our BSD boxes and the fedora box.
> > 
> > 10.11.1.91:/data/online          /mnt/online    nfs    
> rw,port=2049,intr    0    0
> > 
> > We then have a /online ->/mnt/online
> > 
> > Fedora says the default is v2.
> > 
> > I am not sure what the 0   0 are doing at the end of the mount but
> they were on the freebsd boxes so I just left them.
> > 
> > Is there away to make sure that we are allowing enough connections
> on the NFS server?
> > 
> > let me know what you see.
> > 
> > thanks,
> > Adam
> > 
> > 
> > ----- Steve Alligood <steve at bluehost.com> wrote:
> >> it may be HOW you are mounting it, and how fedora versus BSD
> defaults
> >> to 
> >> mount it.
> >>
> >> nfs v2 will be really quick, but not as reliable for data writes
> (aka,
> >> udp)
> >>
> >> nfs v3 will be more reliable (tcp) but slower
> >>
> >> nfs v4 will be reliable (tcp) and secure (encrypted) but a lot
> slower
> >>
> >> Fedora may default to v4 while your BSD does v3 or v2.
> >>
> >>
> >> I have some mounts I use nfs v2 because I am not as worried about
> >> writes 
> >> and I need the speed.  I also change the read and write window
> sizes,
> >>
> >> and turn off atime checking:
> >>
> >> async,soft,noatime,intr,nfsvers=2,rsize=8192,wsize=8192
> >>
> >> Of course, the server must support the v2 nfs as well (obvious, but
> 
> >> worth mentioning)
> >>
> >> -Steve
> >>
> >> adam fisher wrote:
> >>> I appreciate everybody's thoughts on this.
> >>>
> >>> I agree that the NFS looks to be the bottle neck however we have
> 5
> >> other load balanced web servers that are pulling the web data from
> our
> >> NFS server.  We mount the partition and then created sym links to
> >> those mounts.  The other 5 web boxes are up and running fine.  It
> is
> >> the sixth alone that is having this issue.
> >>> The first 5 are BSD this is a Fedora installation as we want to
> get
> >> away from BSD.  
> >>> Any other ideas?
> >>>
> >>> thanks,
> >>> Adam
> >>>
> >>>
> >>> ----- Ryan Simpkins <plug at ryansimpkins.com> wrote:
> >>>> On Wed, March 28, 2007 11:44, adam fisher wrote:
> >>>>> apache   17268  0.7  0.6  29552 12868 ?        D    04:27  
> 0:04
> >>>> /usr/sbin/httpd
> >>>>> apache   17456  1.1  0.6  29728 13168 ?        S    04:27  
> 0:06
> >>>> /usr/sbin/httpd
> >>>>> apache   17890  0.5  0.6  29928 12588 ?        D    04:28  
> 0:02
> >>>> /usr/sbin/httpd
> >>>>> apache   17893  0.0  0.5  29032 11548 ?        D    04:28  
> 0:00
> >>>> /usr/sbin/httpd
> >>>>> apache   17895  0.0  0.5  29184 11716 ?        D    04:28  
> 0:00
> >>>> /usr/sbin/httpd
> >>>>> apache   17896  0.0  0.5  28740 11256 ?        D    04:28  
> 0:00
> >>>> /usr/sbin/httpd
> >>>>> apache   17897  0.0  0.5  28912 11452 ?        D    04:28  
> 0:00
> >>>> /usr/sbin/httpd
> >>>>> apache   17904  0.3  0.5  29288 11876 ?        D    04:28  
> 0:01
> >>>> /usr/sbin/httpd
> >>>>> apache   17913  0.5  0.5  29316 11892 ?        D    04:29  
> 0:02
> >>>> /usr/sbin/httpd
> >>>>> apache   17923  0.1  0.5  29364 12052 ?        D    04:29  
> 0:00
> >>>> /usr/sbin/httpd
> >>>>
> >>>>> Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s
> >>>> avgrq-sz avgqu-sz
> >>>>> await  svctm  %util
> >>>>> sda               0.00    11.00  0.00  6.00     0.00   136.00  
> 
> >>>> 22.67     0.00
> >>>>> 0.50   0.17   0.10
> >>>>> The web root is located on an NFS share.  I restarted NFS on
> this
> >>>> box just to make
> >>>>> sure.  When I restart httpd and the load average drops to
> around
> >> 10
> >>>> or 11 I can
> >>>>> browse the webpage just fine.  It is when it gets to around 150
> >> that
> >>>> I can't.
> >>>> Bingo. Your web root is running over NFS. NFS is pure evil for
> >> this
> >>>> type of work.
> >>>> You may be able to improve performance playing around with the
> >> various
> >>>> NFS mount
> >>>> options.
> >>>>
> >>>> -Ryan
> >>>>
> >>>> /*
> >>>> PLUG: http://plug.org, #utah on irc.freenode.net
> >>>> Unsubscribe: http://plug.org/mailman/options/plug
> >>>> Don't fear the penguin.
> >>>> */
> >>>
> > 
> >







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