Elliswilson: Created page with "Lustre supports three primary backup strategies. Each serves different needs, and most production sites use a combination. {| class="wikitable" |- ! Strategy !! Scope !! Speed !! Granularity !! Best For |- | File-level backup || Client-side || Slow for large FS || Individual files || Selective/incremental backups |- | Device-level backup || Per-target (MDT/OST) || Fast (streaming) || Entire device || Disaster recovery, hardware replacement |- | lustre_rsync || Changelog..."

2026-07-20T15:27:34Z

Created page with "Lustre supports three primary backup strategies. Each serves different needs, and most production sites use a combination. {| class="wikitable" |- ! Strategy !! Scope !! Speed !! Granularity !! Best For |- | File-level backup || Client-side || Slow for large FS || Individual files || Selective/incremental backups |- | Device-level backup || Per-target (MDT/OST) || Fast (streaming) || Entire device || Disaster recovery, hardware replacement |- | lustre_rsync || Changelog..."

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Lustre supports three primary backup strategies. Each serves different needs, and most production sites use a combination.

{| class="wikitable"
|-
! Strategy !! Scope !! Speed !! Granularity !! Best For
|-
| File-level backup || Client-side || Slow for large FS || Individual files || Selective/incremental backups
|-
| Device-level backup || Per-target (MDT/OST) || Fast (streaming) || Entire device || Disaster recovery, hardware replacement
|-
| lustre_rsync || Changelog-based || Incremental || File-level || Continuous replication to second filesystem
|}

== File-Level Backup (Client-Side) ==

Performed from a mounted Lustre client using standard backup tools (<code>tar</code>, <code>rsync</code>, <code>cp</code>, commercial backup software).

'''Advantages:'''
* Integrates with existing backup infrastructure.
* Selective — back up specific directories, users, or projects.
* Can run from multiple clients in parallel (each handling different subdirectories).

'''Procedure:'''
<pre>
# Example: tar backup of a subdirectory
tar czf /backup/project_a.tar.gz /mnt/testfs/project_a

# Example: rsync to a backup server
rsync -av --xattrs /mnt/testfs/project_a/ backupserver:/backup/project_a/
</pre>

'''Key considerations:'''
* Use <code>--xattrs</code> with rsync/tar to preserve Lustre extended attributes (striping, project IDs).
* For very large filesystems, full backups may be impractical. Use incremental backups by date (<code>find -newer</code>) or changelogs.

== Device-Level Backup ==

Uses <code>dd</code>, <code>e2image</code>, or <code>zfs send</code> to create an image of an individual MDT or OST device.

'''Advantages:'''
* Streaming speed — much faster than file-level for full backups.
* Captures entire device state, including internal metadata.

'''Procedure:'''
<pre>
# ldiskfs: device image backup
umount /lustre/testfs/mdt0
dd if=/dev/sda1 of=/backup/mdt0.img bs=1M

# ldiskfs: space-efficient backup (skips unused blocks)
e2image -ra /dev/sda1 /backup/mdt0.e2i

# ZFS: send snapshot
zfs snapshot tank/mdt0@backup-20260429
zfs send tank/mdt0@backup-20260429 > /backup/mdt0.zfs

# ZFS: incremental send
zfs send -i tank/mdt0@previous tank/mdt0@backup-20260429 > /backup/mdt0-incr.zfs
</pre>

'''Key considerations:'''
* The target should be unmounted or have a consistent snapshot (LVM snapshot or ZFS snapshot) before backup.
* Device-level backups cannot selectively restore individual files.

== lustre_rsync (Changelog-Based Replication) ==

Uses Lustre changelogs to replicate changes from a source Lustre filesystem to a target filesystem. Ideal for maintaining a warm standby or replicating to a remote site.

See [[Lustre Rsync Replication]] for full setup instructions.

== Decision Tree: Which Strategy to Use ==

<pre>
Need to restore individual files?
YES → File-level backup
NO → Continue

Need disaster recovery for a single target device?
YES → Device-level backup
NO → Continue

Need continuous replication to a standby filesystem?
YES → lustre_rsync
NO → Continue

Default recommendation:
- MDT device-level backup (weekly) — CRITICAL
- File-level incremental backup (daily) for important data
- lustre_rsync for sites that need warm standby
</pre>

=== MDT Backup Is Critical ===

'''Always maintain regular MDT backups.''' The MDT contains all filesystem metadata — file names, directory structure, file layouts, permissions, and striping information. Losing the MDT without a backup means losing the entire filesystem namespace, even if all OST data is intact.

An MDT is typically a few TB at most, so device-level backups are fast and practical. Even a week-old MDT backup is vastly preferable to total filesystem loss.

== Target-Level Filesystem Backup ==

An alternative to raw device images: use <code>tar</code> or <code>rsync</code> on the underlying MDT/OST filesystem (mounted as ldiskfs or accessed via ZFS). This preserves the data but allows changing formatting parameters (inode ratio, filesystem features) on restore.

<pre>
# Mount the backend filesystem
mount -t ldiskfs /dev/sda1 /mnt/mdt0_backend

# Backup with xattrs preserved
tar cf /backup/mdt0_files.tar -C /mnt/mdt0_backend --xattrs --xattrs-include='*' .
</pre>

This takes longer than <code>dd</code>/<code>e2image</code> due to per-file overhead, but uses less space than a full device image.

== See Also ==

* [[Lustre Rsync Replication]]
* [[Backing Up a Lustre File System]]

[[Category:Lustre Systems Administration]]
[[Category:Lustre Backup and Recovery]]

Lustre Backup Strategies - Revision history