On Wed, Oct 12, 2016 at 03:35:34PM +1100, russell@coker.com.au wrote:
On Wednesday, 12 October 2016 2:46:01 PM AEDT Craig Sanders via luv-main wrote:
yes, but you can't pipe `btrfs send` to `zfs recv` and expect to get anything useful. my backup pool is zfs.
In the early days the plan was to have btrfs receive not rely on BTRFS, so you could send a snapshot to a non-BTRFS filesystem. I don't know if this is a feature they continued with.
nope. from what i've read, they originally intended to make it tar compatible but tar couldn't do what they needed, so they dropped that idea.
Last time I was buying there wasn't much price difference between SATA and NVMe devices. Usually buying 2 medium size devices is cheaper than 4 small devices.
right, but there's a difference between the price of Crucial SSDs and Samsung or Intel. There's also a price difference between having to buy a pci-e nvme card and not having to buy one.
PCI-e slots are in very short supply. and my m/b doesn't have any nvme sockets.
That's a problem for you then.
well, yes, of course it is. we're talking about my system here, and why I choose 4 cheap SATA SSDs rather than two pci-e SSDs.
i'd still want to buy them in pairs, for RAID-1/RAID-10 (actually, ZFS mirrored pairs)
The failure modes of SSD are quite different to the failure modes of spinning media. I expect it will be some years before there is adequate research into how SSDs fail and some more years before filesystems develop to work around them. ZFS and WAFL do some interesting things to work around known failure modes of spinning media, they won't be as reliable on SSD as they might be because of the spinning media optimisation.
I'd still use some kind of raid-1/mirroring anyway, no matter what kind of drives I had. raid isn't a substitute for backups, but it does reduce the risk that you'll need to restore from backup (and the downtime and PITA-factor that goes along with restoring) also, there's no way for ZFS to correct any detected errors if there's no redundancy. i don't mind paying double for storage. it's a bit painful at purchase time, but that's quickly forgotten. and a lot less painful than the time and hassle required to restore from backup, and losing everything new or modified since the previous backup (nightly, but that's still up to a full day's worth of stuff that could be lost. Now that i've got rootfs on ZFS, I can snapshot frequently and backup more often with zfs send) craig -- craig sanders <cas@taz.net.au>