Mailinglist Archive: yast-devel (144 mails)

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Re: [yast-devel] Transactional upgrades using the filesystem
  • From: Olaf Dabrunz <Olaf@xxxxxxxxxxx>
  • Date: Mon, 4 Feb 2008 17:36:11 +0100
  • Message-id: <20080204163610.GA8013@xxxxxxx>
On 03-Feb-08, Duncan Mac-Vicar P. wrote:

We have some features open for rollbacks on upgrades. Give a look at this:

"There is no ideal software, it always has bugs. Minor, major or
security issues will always exist and modern operating systems need to
deal with this fact. What if any software which user installs had a
capability to rollback to previously known successful point and
operation itself would take no time? What if developer or user has a
tool which could checkpoint operating system and capability to revert
changes in no time? This is possible if we will marry two great
technologies: ZFS and Debian APT
<http://www.nexenta.org/os/TransactionalZFSUpgrades>. Both technologies
now part of Nexenta Operating System which is core foundation for its
derivative distributions. Meet apt-clone
<http://www.nexenta.org/os/AptCloneMan>. The tool which integrates with
the NexentaCP system, keeps track of upgrade checkpoints and allows to
create/destroy/edit checkpoints by request."

http://osnews.com/story/19180/Transactional_Debian_Upgrades_with_ZFS_on_Nexenta

I do not see why ZFS would be required. AFAICS, only the snapshot
functionality is required. This is available through LVM for any
filesystem.

If we are only required to be able to roll back the "software and system
configuration" (rather than user data), this can be quite reliable. The
number of applications that we have to control or at least be aware of
to assure a consistent state of the data in the files, is relatively
small (mainly rpm should not run while taking a snapshot).

So, to be able to support this, we would require a snapshot
functionality of the "system partition", which means LVM for the system
partition ATM (ZFS support could be added later, if needed). Should we
use LVM for this partition by default?

(AFAICR we do not need to consider EVMS anymore...)

--
Olaf Dabrunz (Olaf <at> dabrunz.com)

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