Older News

2010-03-15

The host stabile.debian.org is once again creating snapshots as snapshot-master, all the data from the secondary setup on sibelius have been merged, so all is back to normal.

2010-03-09

In the meantime we found a new controller and snapshot-master now is back online. One disk in one of the four RAID-6 arrays has also failed and we are looking into replacing that soon.

The secondary setup on sibelius has faithfully continued to do snapshots (except for backports.org for which we somehow failed to get pushed) and we are in the process of merging those new snapshots into the database on master.

The disk related problems raised some concerns about data integrity. The actual data of snapshot is kept in the farm, a content addressed file system. That is to say that all files are named by the SHA-1 hashsum of their content. The metadata which links hashes to packages and files in snapshotted archive trees is stored in a PostgreSQL database. To verify the health of the farm we have implemented a rudimentary fsck which verifies two things:

• First, that all the filenames match their actual content. This check turned up several mismatches. In four instances the file on disk actual had the correct content as referenced by Release and Packages files, but for some reason we calculated the wrong hash during import time. Yay. This was relatively easy to repair as it only required renaming the files on disk and updating all references in the database.
  Then there were some 20 or 40 files with the same checksum (the hash of the empty file), as a result of XFS failing to write the files' contents when the disks went away two weeks ago. Given that those import runs' metadata never got committed in PostgreSQL either we could simply remove those files.
  Another four files of the two latest mirrorruns of the debian archive that did make it to our database actually turned out to be corrupt. In all likelihood also as a result of XFS not liking it when suddenly its block device disappears partially. The files in questions were Packages.{gz,bz2} of the sid installer for amd64 and s390. The corrupted files have been removed. We are considering trying to reconstruct those files from the rest of the ftp tree (it should after all just be an apt-ftparchive run), but it is not a very high priority.
• The other check verified that for each hash referenced in the PostgreSQL database we actually have the corresponding item in the farm. No errors were found by this check (except the four files reportedly removed above).

We are also currently importing historical snapshots of the debian-ports ftp tree as requested in Bug #571118.

If all goes well we should be back to a normal state in a couple of days. Then we have to deal with removing things that got removed from the source archives due to licensing problems. Once that last hurdle is taken we can finally announce it and make it an official service.

2010-02-24

So we finally got a second machine up and serving a copy of snapshot. Of course this means that now a disk controller breaks in the snapshot-master machine and thus half of our disks are rendered inaccessible. Even raid6 doesn't like that very much.

Therefore snapshot will not get any new data currently and the service is provided by only one of the servers of what was previously a DNS round robin rotation.

We had planned to eventually set up a secondary snapshot master that would do the import runs into an alternate database for just such occasions. This occurrence prompted us to somewhat expedite that project.

So while currently snapshot will not get any updates we should be able to inject most mirrorruns into snapshot-master when it gets back. We'll have lost a few runs of volatile and the main debian archive, but we should not see a gap longer than roughly a day.

2010-02-20

Finished setting up mirroring scripts. While snapshot-master (stabile) still is the entity importing new snapshots into the system all the data is now replicated to a secondary site (sibelius). The web front-end runs on both of them.

Application Developed by Peter Palfrader — Web/Graphics designed by Bernhard Weitzhofer
Source code can be cloned with git clone https://salsa.debian.org/snapshot-team/snapshot.git or browsed directly on salsa.debian.org.
Please report bugs against the snapshot.debian.org package.
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