So- I upgraded mysql from 5 to 5.1.49 on Debian Lenny using the dotdeb repositories, and it borked out.
Being a somewhat ham handed admin, and it being Christmas morning and all, I decided to take the plunge and upgrade from Lenny to squeeze. That upgrade went fine, but mysql still wouldn't upgrade *or* downgrade back to 5.

101225  8:52:07 [Warning] option 'thread_stack': unsigned value 65536 adjusted t
101225  8:52:07 [Note] Plugin 'FEDERATED' is disabled.
101225  8:52:07 [Note] Plugin 'InnoDB' is disabled.
101225  8:52:07 [ERROR] /usr/sbin/mysqld: unknown option '--skip-bdb'
101225  8:52:07 [ERROR] Aborting

101225  8:52:07 [Note] /usr/sbin/mysqld: Shutdown complete

Starting MySQL database server: mysqld . . . . . . . . . . . . . . failed!
invoke-rc.d: initscript mysql, action "start" failed.
dpkg: error processing mysql-server-5.1 (--configure):
 subprocess installed post-installation script returned error exit status 1
configured to not write apport reports
                                      Errors were encountered while processing:
 mysql-server-5.1

Anyway- the fix was to use a new my.cnf file. Apparently there are some changes and the old ones will not work.
I did

linpear:~# cp /etc/mysql/my.cnf /etc/mysql/my.cnf.mine
linpear:~# cp /etc/mysql/my.cnf.dpkg-dist /etc/mysql/my.cnf

did an -f install, and all is well.
[/code]Hope this helps someone- and now I have a shiney new Squeeze install, running the latest linode paravirt kernel.

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Chris Bryant

You should check those default params against your size of linode, you might have too much memory specified.

Yes- I did go back and edit the new my.cnf file with my old values, which for some reason worked fine.

There are still some oddities though, with Squeeze, Apache 2.2.16, PHP 5.3.3-6, and MySql 5.1.54, I am using more memory, though Munin shows about the same used, but a *lot* more committed.

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Chris Bryant