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Not in the slightest. I'd rather have some redundancy up front than try to restore a bunch of junk from backups. Backups are important, but not ever having to

Not in the slightest. I'd rather have some redundancy up front than try to restore a bunch of junk from backups. Backups are important, but not ever having to use them is even better. Not only that, but having RAID or mirror sets gives you flexibility in ways that you might not think about up front. For instance, I just replaced some old 750GB disks with new 5TB disks. I added the new 5TBs to the the mirror set and let it bring all the data across automatically. When it was done, I dropped the 750s out and resized the raid set to use the whole 5TB (I told it it was already clean so it didn't have to sync up a bunch of unused space). Then, finally, I resized the filesystem that was mounted on that mirror set. This was all done live, with data actively being read and written to while all this volume manipulation stuff was happening. That is why you use RAID at home (and lvm, too).

joosters 11y ago
Alternatively, * Plug new hard drive in * cp data on to new hard drive * ...profit? IMO, much simpler, straightforward, less prone to errors and your data is perfectly safe until you do something with the old hard drive. Again, it's not 100% uptime but this is your home, not a mission-critical business.
- __david__ 11y ago
  Not much simpler. Replacing my disk as described above was literally 4 commands from bash. And zero reboots. And less error prone? Are you joking? In a non-mirror system you have to re-partition and set everything up the way it was, you have to really hope you copy things back correctly (do you have a bunch of hard links? Does cp copy them correctly? What's that option to rsync again? Do you have enough memory to copy hard links correctly? Are xattrs going to copy correctly?). Sigh. On top of that all you can't actually use that disk while any of this is happening. Grrr, and it's going to take 11 hours to copy 5 TB of data back (at 125MB/s)! If you're perfectly happy with your computer being out of commission for 11 hours, be my guest. Also, when the old disk is removed from the mirror set, it's a complete image copy of the data. I'm not sure why you think that isn't the case... Seriously, making every disk in your computer a mirror set is really a phenomenal idea. I've been doing it for years now and every time I have to upgrade or replace a disk it's made it heavenly. You shouldn't pooh pooh it until you've actually tried it.
sp332 11y ago
Backups are more useful to me, because RAID won't save you from a wayward rm -f.
- doublerebel 11y ago
  RAID itself won't, but ZFS snapshots roll back nearly instantly from a rm -f. Can't imagine living without them for home or business these days.
snowwrestler 11y ago
RAID is not a replacement for backups; they do different things. RAID preserves performance and/or uptime in the face of hardware failures. It does not protect against data corruption or deletion. It will happily sync those across all your disks. Backups protect against any data loss: hardware, software, even intentional. The key feature of a backup is that it is insulated from live data operations (including RAID sync).
- __david__ 11y ago
  I never said it was a replacement. I wholeheartedly agree that backups are indispensable, but when dealing with drive failure, I'd rather just swap out a drive and not have to deal with restoring from backups. I find backups are good for fine grained laser focused restores—trying to restore an entire drive is either slow, or error prone, especially if one deals with hard links a lot.

joosters 11y ago

Alternatively, * Plug new hard drive in * cp data on to new hard drive * ...profit? IMO, much simpler, straightforward, less prone to errors and your data is perfectly safe until you do something with the old hard drive. Again, it's not 100% uptime but this is your home, not a mission-critical business.

__david__ 11y ago
Not much simpler. Replacing my disk as described above was literally 4 commands from bash. And zero reboots. And less error prone? Are you joking? In a non-mirror system you have to re-partition and set everything up the way it was, you have to really hope you copy things back correctly (do you have a bunch of hard links? Does cp copy them correctly? What's that option to rsync again? Do you have enough memory to copy hard links correctly? Are xattrs going to copy correctly?). Sigh. On top of that all you can't actually use that disk while any of this is happening. Grrr, and it's going to take 11 hours to copy 5 TB of data back (at 125MB/s)! If you're perfectly happy with your computer being out of commission for 11 hours, be my guest. Also, when the old disk is removed from the mirror set, it's a complete image copy of the data. I'm not sure why you think that isn't the case... Seriously, making every disk in your computer a mirror set is really a phenomenal idea. I've been doing it for years now and every time I have to upgrade or replace a disk it's made it heavenly. You shouldn't pooh pooh it until you've actually tried it.

sp332 11y ago

Backups are more useful to me, because RAID won't save you from a wayward rm -f.

doublerebel 11y ago
RAID itself won't, but ZFS snapshots roll back nearly instantly from a rm -f. Can't imagine living without them for home or business these days.

snowwrestler 11y ago

RAID is not a replacement for backups; they do different things. RAID preserves performance and/or uptime in the face of hardware failures. It does not protect against data corruption or deletion. It will happily sync those across all your disks. Backups protect against any data loss: hardware, software, even intentional. The key feature of a backup is that it is insulated from live data operations (including RAID sync).

__david__ 11y ago
I never said it was a replacement. I wholeheartedly agree that backups are indispensable, but when dealing with drive failure, I'd rather just swap out a drive and not have to deal with restoring from backups. I find backups are good for fine grained laser focused restores—trying to restore an entire drive is either slow, or error prone, especially if one deals with hard links a lot.