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Ripristino di Sistema con Btrfs

Sommario

Se l'utente sceglie di usare Brtfs su una o più partizioni, allora potrà:

  • creare automaticamente nuove immagini di disco minime prima di ogni transazione yum
  • scegliere da quale immagine minima avviare il sistema
  • creare manualmente una nuova immagine minima

Tutte le opzioni indicate richiedono i privilegi di root.

Progettista

Stato corrente

Descrizione dettagliata

Btrfs serve a creare un'immagine minima del filesystem che può essere montata (e da cui si può avviare il sistema) in maniere selettiva. Le immagini create sono ottimizzazioni copy-on-write, in modo da non avere il sovraccarico di file duplicati quando non sono presenti cambiamenti.

It's important to note that these snapshots are whole-filesystem snapshots -- while we propose to create a new snapshot each time a yum transaction happens, that doesn't mean reverting to an earlier snapshot will only revert the files changed by yum! The entire root filesystem will be reverted, including users' home directories if they are on btrfs. (Because of this, a user may decide to keep /home on a separate, non-btrfs partition where it is unaffected by rollbacks they decide to initiate.)

A "rollback" to an older snapshot is not destructive to data. It switches to an earlier snapshot, and later snapshots are still available afterwards. We allow the user to choose which snapshot will be mounted next, and making that choice does not affect or destroy any other snapshots.

We are not proposing Btrfs to be the default filesystem for Fedora 13; this feature would only be present on installs where Btrfs has been optionally chosen for at least one filesystem.

Vantaggi per Fedora

Esistono diversi casi d'uso interessanti a proposito di questo progetto:

  • Aaron is a developer whose laptop tracks Rawhide daily. There will be days where Rawhide is not bootable/usable, though. When Rawhide breaks, automated snapshots allow Aaron to easily revert to the previous day's filesystem until Rawhide's known-working again.
  • Barbara wishes to bisect a mysterious bug that appears to have crept in on one of her recent Rawhide updates. Performing the full-system bisection is made easier by binary searching the snapshots on her disk, to narrow down responsibility for the bug to a small list of modified packages and their versions.
  • Christine wishes to create weekly snapshots by hand in case she later wants to have access to older versions of the files she's been working on.
  • Donald has, independent of yum/rpm, somehow hosed his system and doesn't know how to recover it. He'd like to revert back to the last snapshot that was made.

Of these, the ability for our developers to feel comfortable tracking Rawhide without fear of an unusable install seems to have the most immediate utility to Fedora.

Documentazione

Quì è possibile trovare dei documenti di carattere generale su btrfs:

Note di rilascio

Users of the experimental btrfs filesystem in Fedora 13 benefit from automatic filesystem snapshots each time the yum package manager performs an installation or upgrade, and from a user interface to allow switching between snapshots.

Altre informazioni

Per:

  • Obbiettivi
  • Test Plan
  • Esperienza Utente
  • Dipendenze
  • Progetto corrente
  • Commenti e Discussioni

consultare la pagina originale di questo documento.

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