will yum update delete all my databases? settings? etc.

I just hosed my Centos install and I'm wondering whether to do a yum update? I have loads of mysql and solr databases that I am working on. Will it delete those? Should I do a backup before doing a yum update?

From serverfault Ke

• Yes making a backup is ALWAYS the right answer.

  No using package managers like yum to upgrade your system will not mess with your data.

  The only caveat is that sometimes data formats change between versions of software. For example the data storage format mysql uses might change, and the upgrade scripts might help you convert your data to the new system, but it is very unlikely that a package upgrade like this will actually break your data. Also backups are the right thing to do because if anything goes wrong with system updates such as an unbootable system on a kernel upgrade, that backup will be nice to have in your pocket.

  From Caleb

• First, you should always be doing backups. Irrespective of performing any updates, performing backups are simply a requirement for sysadmins.

  It's not clear what you mean by "hosed my Centos install", so it's tough to say if any yum operations would be helpful. But in genreal, no, yum update will not delete existing databases.

  Ke : thx :), by "hosed" i mean that I uninstalled alsa on centos and it deleted like every package from centos. Will doing a yum update help?

  jscott : @Ke `yum update` probably won't fix it. You should try to re-install alsa and, hopefully, any dependencies, with something like `yum install alsa alsa-drivers`. Failing that, perform a clean install and restore your data from backup.
  From jscott

• It depends on the quality of the package. If the package is written sanely then it will not affect your data in any way. Almost all first-party packages are sane.

  From Ignacio Vazquez-Abrams

• Never do anything you're unsure of out of desperation. Always have a backup even if you think you know what will happen.

  From Bryan White