Sujet : backup

• libvirt storage pools and qcow2 snapshots are not a backup

  virsh snapshot-create-as makes internal qcow2 snapshots fast to create, but they live inside the same disk image as the guest and depend on that image surviving. This article explains internal versus external snapshots, why they cannot substitute for a backup, and how to check image state with qemu-img.

  article · en · reviewed · connaissances au 2026-09-24

• Backing up and restoring a Windows Server with Windows Server Backup (wbadmin)

  Installing the Windows Server Backup feature, running a full or system state backup with wbadmin start backup / start systemstatebackup, listing recovery points with wbadmin get versions, what the tool does not cover, and testing a restore rather than assuming one will work.

  methodology · en · reviewed · connaissances au 2026-09-24

• Backing up and cloning AIX: mksysb, savevg, and low-risk upgrades with alt_disk_copy

  mksysb creates a bootable backup of rootvg (savevg backs up a non-root volume group, not bootable, restored with restvg); lsmksysb reads back what a mksysb image contains without restoring it. alt_disk_copy and alt_disk_mksysb clone or update rootvg onto a spare disk so a bootlist change, not a restore, is the fallback if the new level misbehaves.

  methodology · en · reviewed · connaissances au 2026-09-24

• Btrfs snapshots and rollback with snapper on SUSE: pre/post pairs, GRUB boot, and cleanup

  On a Btrfs root, SUSE's snapper takes a pre/post snapshot pair around every zypper or YaST change, lists them with snapper list, and can either roll the whole system back or boot directly into an old snapshot from the GRUB menu. Old snapshots are cleaned up automatically, but the cleanup policy — not disk size alone — decides how much history is kept.

  methodology · en · reviewed · connaissances au 2026-09-24

• Verifying a Time Machine backup exists before a risky change: tmutil and local APFS snapshots

  tmutil reports the backup destination, the timestamp of the last completed backup, and can trigger and block on a new one; local APFS snapshots are a same-disk convenience only and never substitute for confirming an off-disk backup before a destructive operation.

  methodology · en · reviewed · connaissances au 2026-09-24

• ZFS boot environments with bectl: a rollback path around FreeBSD and package upgrades

  bectl clones the root ZFS dataset into a boot environment in seconds; creating one before a freebsd-update or large pkg upgrade gives an instant, loader-menu-selectable way back to a known-good system, independent of and in addition to freebsd-update's own patch/install/rollback machinery.

  methodology · en · reviewed · connaissances au 2026-09-24

• IBM i backups: SAVLIB, SAVOBJ, SAVSYS, save files, and the GO SAVE menu

  IBM i backups revolve around SAVLIB/SAVOBJ/SAVSYS writing to tape or to a save file created with CRTSAVF, and the GO SAVE menu options that wrap them into repeatable, optionally unattended, full or partial system saves.

  methodology · en · reviewed · connaissances au 2026-09-24

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