On 3/17/23 12:36, Gregory Seidman wrote:
On Fri, Mar 17, 2023 at 06:00:46PM +0300, Reco wrote: [...]PS There's that old saying, "RAID is not a substitute for a backup". What you're trying to do sounds suspiciously similar to an old "RAID split-mirror" backup technique. Just saying.This thread has piqued my interest, because I have been lax in doing proper backups. I currently run a RAID1 mirroring across three disks (plus a hot spare). On top of that is LUKS, and on top of that is LVM. I keep meaning to manually fail a disk then store it in a safe deposit box or something as a backup, but I have not gotten around to it. It sounds to me like adding an iSCSI volume (e.g. from AWS) to the RAID as an additional mirror would be a way to produce the off-site backup I want (and LUKS means I am not concerned about encryption in transit). It also sounds like you're saying this is not a good backup approach. Ignoring cost, what am I missing?Reco--Gregory
I would not consider using a cloud device as a RAID member -- that sounds both slow and brittle. Live data needs to be on local hardware.
I have considered putting an encrypted filesystem on top of a cloud volume -- but, that sounds brittle; both for live data and for backups.
I have put encrypted tarballs in cloud filesystems (e.g. archives) -- KISS; I like it.
On 3/17/23 13:52, Dan Ritter wrote: > Three different things: > > resiliency in the face of storage failure: RAID. > > restoration of files that were recently deleted: snapshots. > > complete restoration of a filesystem: backup. > > (and technically, a fourth: complete restoration of points in > time: archives). > > You can combine the approaches, but they can only be substituted > in particular directions. A RAID alone doesn't give you > protection against deleted files (or deleted filesystems), which > is what a backup is for. > > -dsr- +1 I would add: * ECC memory. * Check-summing filesystems (I prefer ZFS-on-Linux). * Multiple backup media in rotation. * Another computer for taking backups, doing restores, etc..With four disks, the OP could use two in a ZFS mirror for live data, use zfs-auto-snapshot for user-friendly recovery, and use the other two individually as on-site and off-site backup media.
David