[CentOS] Anyway to ensure SSH availability?

[Les Mikesell]

On 6/29/2011 4:12 PM, Emmanuel Noobadmin wrote:
> On 6/30/11, Robert Heller<heller at deepsoft.com>  wrote:
>> If the problem is excessive load because Sendmail / Mimedefang / spamd /
>> etc. is too busy handling tons of mail/spam being dumped on your server, you
>> might want to look at these sendmail options:
>
> Mail was my first suspect because I had similar issues with exim/spamd
> locking up bad on another server. But usually that includes a high cpu
> % as well. Although this suspicion did help me pinpoint one of the
> causes, a script that periodically went through the email
> accounts/Maildirs and that was fixed from learning about ionice on the
> list.
>
> For a while I thought problem solved, but these couple of days, it's
> acting up again and nothing's jumping out screaming "I'm the problem!"
> and not being able to SSH to see what's exactly going on is making it
> difficult.

What's the physical disk system?  I remember seeing something like that 
long ago where a raid controller had a large write cache that normally 
made it seem fast, but once in a while either filling it to a high-water 
mark or something else would trigger it to complete catch up before 
responding again - which could take several minutes with everything 
blocked.  And nothing else ever looked out of the ordinary.

-- 
   Les Mikesell
    lesmikesell at gmail.com