I was very excited when I realised, that Netgear is now using btrfs. Mainly because it would help a lot when changing disk in a raid0 without the need of destrying the complete raid. (I dont use raid >= 1, because there has to be a backup elswhere any way....)
So I played around a little with my RN104 btrfs,but realised, that Netgear "only" managed to format an LVM Raid partition with btrfs. Okay, yes, there are benefits from Bitrot, and snapshot functionality... BUT, btrfs knows nothing from the physial devices, hence it cant profit from that.
Did any one know, if Netgear is planing to use BTRFS not only as a way to format a normal LVM partition?
What kind of RAID-0 volume would you want? A separate one for each disk? with that it would be quick to create a new volume on a new disk that you add. Swapping disks out isn't meant for backups. It's meant for replacing a dead disk or a disk you no longer wish to use (with a higher capacity one).
I think you meant md raid not LVM RAID. We are not using LVM. OS4 used EXT4 on top of LVM on top of md raid. Now we use BTRFS on md raid.
While the BTRFS filesystem is stable, BTRFS level RAID is still quite experimental (especially RAID5 and RAID6) in my personal view and I would not trust it. Whereas md raid has been around for over a decade and is very mature.
As for what we will do in the future you will have to wait and see.
What kind of RAID-0 volume would you want? A separate one for each disk?
No, no. I'm not sure, but can't btrfs use logical partitions for building a raid? For example, use sda2 + sdb2 + sdc2 to build a raid-n?
mdgm wrote:
Swapping disks out isn't meant for backups. It's meant for replacing a dead disk or a disk you no longer wish to use (with a higher capacity one).
yes, eactly. Every time when expanding my NAS's (all bays filled), I'll have the problem, that I have to complete restore them from Backup. With Btrfs it would be possible to empty one of the disk ( there must be enough space left on the Raid), take it out of the raid, and mount a bigger one to it.
mdgm wrote:
I think you meant md raid not LVM RAID. We are not using LVM. OS4 used EXT4 on top of LVM on top of md raid. Now we use BTRFS on md raid.
This may be, I'm not that "linux expert". 😉
mdgm wrote:
While the BTRFS filesystem is stable, BTRFS level RAID is still quite experimental (especially RAID5 and RAID6) in my personal view and I would not trust it. Whereas md raid has been around for over a decade and is very mature.
yes, I heard about it. But may be, it will become stable some time. And because I'm not using raid >0 (didn't need to ensure 100% data access) raid 0 would be quite fine for me... 🙂 (okay, yes, there may exist some other users, which have to rely on Raid5/6)
mdgm wrote:
As for what we will do in the future you will have to wait and see.
Integrating raid-like features into the file system itself has a lot of advantages, so it is an industry trend worth watching.
Gonzo-already_in_use wrote:
...okay, yes, there may exist some other users, which have to rely on Raid5/6...
I think you've answered your original question here.
ReadyNAS expands from single disk jbod to raid-1 to raid-5 automatically, and the automatic expansion feasure is very important to the bulk of the users. If they tried to use the raid-like features in btrfs for jbod and raid-1, they won't be able to expand to md raid-5 w/o a factory reset. Using the experimental features prematurely would cost Netgear customers (very few users are willing to take needless chances with their data integrity).
So instead they developed an alternative way to get bit-rot protection, which gives them most of the benefits of btrfs now, while staying away from experimental features. Later on when they become stable, they can do more.
yes , you are absolut right, and I also understand the way Netgear implemented and uses the feature in its existing environment. And Checksum & COW is most welcome, it secures my backups. No more manual md5 sum checking.
But, the question, if Netgear plans to implement and use the full set of btrfs, should be allowed. From my side, that would simplify the handling while expanding / changing (presupposed a good and simple User interface) of NAS a lot.
And I'll guess, esspecialy those "little" NAS's for home systems, aren't used a lot in professional environments, hence they didn't really need Raid 1/5/6/... . It's rarely a problem at home if I can't access my data for some days. In urgent circumstances I could take it direct from backup. No production line stands still...
Don't get me wrong, all in all I have to say, that I'm really *very* please with my RN104. It's way a lot better then I had expected from that low price (compared to other 4-bay home-NAS). Actually the build quallity easily beats my other systems here. Full implemented Btrfs would just be the icing on the cake... I'm young (more or less...), I can wait .... :wink:
