Re: Anyway to ensure SSH availability?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]



On Thu, Jun 30, 2011 at 03:50:30AM +0800, Emmanuel Noobadmin wrote:
> I was having problems with the same server locking up to the point I
> can't even get in via SSH. I've already used HTB/TC to reserve
> bandwidth for my SSH port but the problem now isn't an attack on the
> bandwidth. So I'm trying to figure out if there's a way to ensure that
> SSH is given cpu and i/o priority.

As you've probably figured out, the short answer is no.  There are
sometimes workarounds, of course.

> Since I'm not the only person who face problems trying to remotely
> access a locked up server, surely somebody must had come up with a
> solution that didn't involve somebody/something hitting the power
> button?

In addition to the suggestions already made, one possibility is to
attach a serial console or IP KVM.  Logging in may still be awful, but
at least you won't have to go through sshd.  I've been able to log in
through a serial getty when sshd was not responding or taking too long
(this works maybe 50-75% of the time; the rest of the time it's too
late, and even getty is unresponsive).  You have the added advantage of
being able to log in directly as root if you have PermitRootLogin no in
your sshd_config.

If your I/O problem is due to running out of memory and thrashing swap,
you can try to be more aggressive with the OOM killer settings.

As someone else mentioned, it might help if you elaborated on "locked
up".  What are the common scenarios you see?

--keith

-- 
kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx

Attachment: pgplq9n82fDqN.pgp
Description: PGP signature

_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos

[Index of Archives]     [CentOS]     [CentOS Announce]     [CentOS Development]     [CentOS ARM Devel]     [CentOS Docs]     [CentOS Virtualization]     [Carrier Grade Linux]     [Linux Media]     [Asterisk]     [DCCP]     [Netdev]     [Xorg]     [Linux USB]
  Powered by Linux