I'd hapily switch to Btrfs or even ext4+LVM but it would mean giving up my problem-free, beginner-friendly backup solution which is CloneZilla. There are few problems with LVM one can stumble upon in a completely standard scenario. Does Btrfs similarly bring difficulties for CloneZilla users?
Or, alternatively, can Btrfs features replace CloneZilla as far as backup goes? Full disk backups capability is a must (including GPT Bios boot partition, /boot partition).
I agree - btrfs is normally slower than ext4, and I say that as someone who uses it on all my systems. It could be that btrfs benefits greatly from SSD caching, which means it'll go great with bcache once the latter is more stable.
Originally Posted by sireangelus
I'm not sure what CloneZilla does, exactly, but Btrfs has LVM features; yet they, naturally, work only in Btrfs partitions. For instance, the UEFI system partition must be FAT32, there is no way around that. And the swap partition must also be a real swap partition (Btrfs doesn't support swapfiles). There are no problems with /boot being a part of the Btrfs partition, though (that's how I have mine set up).
Originally Posted by Bucic
But about backups, there are several things Btrfs supports there. First off is snapshots – cheap to make, yet complete subvolume copies thanks to copy-on-write. Snapper makes them and cleans them automatically with a cron job. YaST and zypper also make pre/post snapshots automatically, too, to allow you to both check what was changed during the session and to roll back changes. On Gentoo I have made a script for myself that creates pre/post snapshots on every non-pretend invocation of emerge for the same reason.
Next we have RAID, of course. Btrfs generally best supports simple mirroring (RAID5/6 are still being worked on IIRC), so that if you have two disks, if one suddenly dies you still have the other with the exact same data (and/or metadata, RAID applies to those independently; very useful in my case, where I have a small SSD and a large HDD – I couldn't mirror the whole HDD contents on the SSD, but I did it with the metadata, and still have space for new data on the SSD).
And then you have btrfs send/receive, which can copy a subvolume/snapshot to another device, and also synchronise it once the original changes (without recopying the entire thing), which means that you can have manual backups on external storage that way. These copies are accessible like any other regular Btrfs file system (except they're by default read-only). So if you want to do something potentially dangerous and want to make a manual full backup, this is the way to go.
I just wonder if this benchmark is really about file-system performance or which file-system works best with the caching algorithm of this hybrid drive. Would be nice to see numbers for real HDDs and SSDs. to rule out such a possibility.
Nicely laid out, thanks.
Originally Posted by GreatEmerald
I know that Btrfs 'has LVM '. That's why I said 'Ext4+LVM or Btrfs'.
However, what puts me off as a beginner is this 'snapshot everything'. For me a zero-zero restore, i.e. ability to restore to a completely wiped-out disk from a backup, is what I need to establish first and foremost. So:
1. Does Btrfs have this ability out of the box (no workarounds/hacks)?
2. Is there a Clonezilla alternative that handles Btrfs in a hassle-free manner?
If you want to be able to make full disk backups, then why don't you just use dd or a frontend to it? Maybe CloneZilla already does that?
The Postmark benchmark on this Solid State Hybrid disk shows no differences between 3.14 and previous kernels, but for the SSD you tested a couple of days ago it showed a large slowdown in performance: http://www.phoronix.com/scan.php?pag...ltrabook&num=2
And what would happen with a HDD I wonder...?
As far as whether its safe... I havent heard of any recent problems in regards to it. But for the sake of cleanliness and neatness, I don't do it. The conversation abuses the fact that Btrfs really doesnt care where the metadata goes, so it just shoves it into unused space of the ext4 layout. Does it work? Of course, but I don't like the frankenstein-filesystem lol.
Originally Posted by siavashserver
One important thing to note if you do the converting.. btrfs will create a ext4_saved subvol under /. Its a snapshot of the drive before the conversion took place. Since its a snapshot, at first it takes up no extra space. But as you use btrfs more and more the differences between the two will grow and you'll eventually take up more and more space than if you had just done a straight install (because it has to keep the old data AND the new data). Only way around this is to delete the snapshot but then you can't go back pre-conversion.
More info here: https://btrfs.wiki.kernel.org/index....sion_from_Ext3
Just a thing to note incase you have a small drive.
The problem with dd and (AFAIK) CloneZilla is exactly why I made this bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1065847
Originally Posted by GreatEmerald
Every linux disk utility does full disk backups via a sector by sector copy, which is great because its filesystem agnostic. But it sucks because you get an image the size of your drive, not the size of your used space because none of them hook into the filesystem utilities and kernel features to figure out what exactly IS used space
SSD benchmarks are queued up for Monday or Tuesday of next week.... HDD results (non-Hybrid) may come later in the week pending interest level; reason using SSHD was at the time of testing I forgot that it was a hybrid drive and the model number not reflecting it so when testing was done I remembered this particular system was my sole hybrid drive system.