Difference between revisions of "Backup"

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Van alle partities (m.u.v. tijdelijke diskruimte zoals /tmp, /var/tmp, /scratch e.d.) wordt 's nachts een backup op een aantal LTO6-tapes gemaakt.
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Van alle partities (m.u.v. tijdelijke diskruimte zoals /tmp, /var/tmp, /scratch e.d.) wordt na elke werkdag een backup op een aantal LTO6-tapes gemaakt.
 
Vanwege de tijd die het kost om een backup te maken, zal dit vaak een zogenaamde ''incrementele dump'' zijn, d.w.z. dat alleen alle veranderingen t.o.v. de laatste backups worden weggeschreven. De backups worden elke avond vanaf 18.00 uur gestart. Deze backup tapes worden ca. vier weken bewaard.
 
Vanwege de tijd die het kost om een backup te maken, zal dit vaak een zogenaamde ''incrementele dump'' zijn, d.w.z. dat alleen alle veranderingen t.o.v. de laatste backups worden weggeschreven. De backups worden elke avond vanaf 18.00 uur gestart. Deze backup tapes worden ca. vier weken bewaard.
 
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All server disk-partitions except temporary space like /tmp, /var/tmp, /scratch, are backed-up nightly on a number of LTO6 tapes.
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All server disk-partitions except temporary space like /tmp, /var/tmp, /scratch, are backed-up after each working day on a number of LTO6 tapes.
 
Because of the time it takes to do a backup, most of the times this is a so-called ''incremental dump'', which means that only
 
Because of the time it takes to do a backup, most of the times this is a so-called ''incremental dump'', which means that only
 
changes w.r.t. the previous backup are written. These backups are started each evening after 18:00 hours. These backup-tapes are preserved for four weeks.
 
changes w.r.t. the previous backup are written. These backups are started each evening after 18:00 hours. These backup-tapes are preserved for four weeks.

Revision as of 14:20, 15 December 2013

If accidentally one or more files are lost from a home-directory (H:-disk) or a /vol-directory, probably the can be restored. On most C&CZ-servers every morning a "snapshot" is taken, on some servers even a few times each day. If one contacts C&CZ system administration the same day, most of the time we can easily restore the situation of that morning with this snapshot. In other cases we have to revert to the backup-tapes to restore the files. To be present on backup-tapes a file must of course be older than one day.

Different independent backup schemes are used:

  • Morning snapshots to disk.
  • Daily backups to tape.
  • Monthly backups to tape.
  • Yearly backups to tape.

Morning snapshots to disk

Many servers take a "snapshot" of their disks at 07:00 hours Monday through Friday, and on some Linux servers at 13:00 hours as well. With this snapshot C&CZ system administration can see the exact situation of that morning, which makes an "undelete" easy. If a user wants to be able to do this himself, C&CZ can create a network share, which makes it possible for the user to look at the snapshot himself from a Windows-PC (or any Samba client).

From a Unix/Linux machine one can attach that network share through:

/usr/local/samba/bin/smbclient //$server/$sharename

or as root through:

mount -t cifs //$server/$sharename /$mountpoint -o user=$user

The regular servers for the home-directories of students and staff are bundle and pile.

We cannot easily share the snapshot filesystem through NFS and an NFS- or CIFS/SMB-server does not follow 'symbolic links', that's why we have to do it as described above.

Daily backup to tape

All server disk-partitions except temporary space like /tmp, /var/tmp, /scratch, are backed-up after each working day on a number of LTO6 tapes. Because of the time it takes to do a backup, most of the times this is a so-called incremental dump, which means that only changes w.r.t. the previous backup are written. These backups are started each evening after 18:00 hours. These backup-tapes are preserved for four weeks.

Monthly and yearly backup to tape

Every weekend a subset of all server disk partitions are completely written to a couple of LTO6-tapes. Every partition is written to tape roughly once every four weeks. These weekly backup-tapes are preserved for one year. The yearly backups are performed in December and are preserved for at least five years.