On 8 February 2012 16:58, Erik Hesselink wrote:

On Mon, Feb 6, 2012 at 19:07, Duncan Coutts wrote:

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On 6 February 2012 15:22, Erik Hesselink wrote:

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Hi all,

We run hackage-server internally at Silk. Every time we update to a new version, it is unable to read our old data. Is the acid-state being versioned correctly? Or is this expected behavior? It is very annoying for us. If this is expected, is there a way to work around it?

Our approach to versioning is not via acid-state by by a database backup/restore method. We export all canonical data to a tarball of text and other standard format files. The reason we do this is because we don't trust that the binary data format is sufficient for long term preservation of all the data. Because we are using dump/restore, we make no attempt to use the acid-state versioning scheme (it's plausible we might do so in future as an extra, but probably not until there are actual releases).

The backu[/restore is done via the commands 'hackage-server backup' and 'hackage-server restore'. It is also possible to generate backups while the server is running by sending a USR1 signal (kill -USR1 $the_pid).

Note also that testing of the backup/restore method is not quite complete, but the testing framework for it is in place I think.

I actually tried the backup at some point, and got the following output:

hackage-server: Initializing happstack-state... hackage-server: Server data loaded into memory hackage-server: Preparing export tarball hackage-server: Saving export tarball hackage-server: Shutting down... hackage-server: /home/erik/state/: inappropriate type

This was with the old code though, I haven't tried with the new code yet.

Ok, like I said it's not fully tested yet, so you may hit some problems that route too, but that's the approach we intend to make work.

I just tried sending the signal to the running process, and got:

hackage-server: Writing checkpoint... hackage-server: Done

There's no backup to be found anywhere, though. Where should it create the backup?

Oh, sorry, I was getting myself confused. Yes, that just writes the acid-state checkpoint, not the backup tarball. We can in principle also do online backup snapshots but we don't have a UI for that yet. Duncan