Plans for upgrading Fritz to Debian Squeeze

1. Preliminaries

Release Note Information of Upgrading From Lenny.

1.1. Pre-Install Cleanup Tasks

1.1.1. Sanitize NSS Configuration

• Synchronize the UIDs of locally created users with their counterparts in AFS

  • docelic_admin

  • rkd_admin

  • clinton_admin

  • adamc_admin

  • shadowfax_admin

• Locate and update any files owned by an obsolete UID to the new UID

• Setup libnss-afs (afs files)

1.1.2. Reconfigure PAM

This may be better to do after the installation.

Configure sshd and login to use pam_localuser instead of pam_unix to ensure only local users can login ignoring the NSS configuration (right now non-local users can't login using just pam_unix, but this is an accident of the implementation of libnss-afs and not something that should be relied upon).

1.2. Pre-Install Software Upgrades

1.2.1. Jabber

The same version of ejabberd must be used across a cluster, and the easiest way to migrate the installation to another machine is to do it with a running cluster. Luckily, deleuze is running the version from etch-backports which is the same version in lenny.

1. Install ejabberd from lenny on fritz

2. Add fritz to the mnesia cluster

3. Add XMPP SRV records to provide both deleuze and fritz

4. Ensure everything works ~24 hours

5. Remove XMPP SRV records pointing to deleuze

6. Ensure everything continues to work for ~72 hours (DNS propagation &c)

7. Disable ejabberd on deleuze

After upgrading fritz to squeeze the ejabberd guide says it will automatically handle updating the mnesia tables. Once this is all done it may be a good idea to add hopper to the ejabberd cluster for a bit of fault tolerance.

2. Installation environment

1. su to root, start a screen session (preventing partial upgrade issues if the network connection drops)

2. Open a physical console root login just in case

3. Installation Steps

3.1. Early Preparations

• dpkg --audit

• Remove lenny and lenny-backports from sources.list

• apt-get update

• Run apt-get upgrade and ensure no essential packages conflict (e.g. postgresql-8.1)

3.2. Backup Important Data

• ejabberd mnesia database

• Debian stuff (package lists, ..., ?)

3.3. Upgrade Kernel and udev

1. Install new kernel image and openafs-module-dkms

2. Install udev

3. Reboot

3.4. Basic Upgrade

1. apt-get upgrade

2. Reboot?

3.5. Full Upgrade

1. apt-get dist-upgrade

2. Reboot?

3.6. Clean Up

1. Make sure the other machines are still sane after losing volume access for a while.

4. Caveats

4.1. pam_unix_session locking all login access

Not an issue

This bit us on hopper. ClintonEbadi has confirmed this is not in use--it appears hopper's PAM configuration was copied from another machine that had been running etch earlier and used deprecated modules.

4.2. Locally built packages

Not an issue

ClintonEbadi scanned the currently installed packages and we are using the backports versions of afs and kerberos with nothing else locally built.

5. Service Interruption Mitigation

5.1. Read Only Volumes on Deleuze

Since we have openafs we may as well take advantage of it by adding deleuze's vicepa as a site for user.$USER volumes. There does not appear to be enough room for mail.$USER volumes so we won't worry about those (mail will still be queued and having a read only copy of mail volumes is of dubious value).

5.1.1. Preparation

A few days before the upgrade:

• Prevent backup from running (uncomment exit 0 in hcoop-backup-wrapper) before scheduled upgrade date

• Purge last backup data

• Purge db.$USER volumes

• Purge {user,mail}.$USER.d volumes for members who departed more than (tentatively) 90 ago

• For all active user.$USER volumes: vos addsite deleuze vicepa user.$USER

Immediately before upgrading:

• For all active user.$USER volumes: vos release user.$USER

5.1.2. Clean Up

For all user volumes vos remsite deleuze vicepa user.$USER to free space for the backup. Alternatively, since the backup will be moved to fritz anyway, leave them in place. There seems to be little benefit to doing so since deleuze does not have much space compared to fritz and we have nothing in place to regularly vos release volumes making them effectively useless.