RAID 5/6 Continues Being Improved For Btrfs With Linux 3.20

[nanonyme]

That's why btrfs only improve slowly and has difficulties to compete with ZFS, btrfs has far too much ambition on its features.

ZFS users were using raid-z anyway

[gilboa]

I'm tired of software raids, I can't even remember how many times my 4 raid1 server re-syncronized hdXA to hdXB for every stupid reason (powerfailure, shutdown problems duo graphics driver bugs, ecc..).
The only way I can accept a Raid configuration it's using raid cards with battery backup.
raid5 or 6? come on! this are stupid and complexity configurations, and for what? better go with raid1 or raid10 with fast and cheap HBAs suitable for get maximum performance from SSDs.
Anyway, I move away from Raid, there are better solutions object level replication with better sync strategies in case of failures.
Ceph and Gluster offer object level replication, great availability and scale out/scale up possibilities.

The wikipage http://en.wikipedia.org/wiki/Btrfs talk about an object level raid but no implementation it's available right now, what a shame.

Weird. I have software RAID on 10+ servers/workstations (some with 8+ drives RAID6 setups) with at least half of them being used for internal kernel development testing, which usually ends with a big-bang (tm).
I can't say that I share your experience.

- Gilboa

[pal666]

I'd like to know if there's any documentation or blog posts etc regarding the current state of RAID 5/6 in btrfs. I'd like to use it but have been avoiding it until it's "ready".

why? raid 1 is faster and more reliable. raid5 is for poor people who have not enough drive space.

[pal666]

That's why btrfs only improve slowly and has difficulties to compete with ZFS, btrfs has far too much ambition on its features.

btrfs had outcompeted zfs long ago

[pal666]

and then the code base can go to sleep / maintenance mode, and then it will be very reliable.

right word for this is 'obsolete'

[Swiftpaw]

why? raid 1 is faster and more reliable. raid5 is for poor people who have not enough drive space.

You love wasting electricity and drive space? Then you're a moron. The entire point of RAID5 and RAID6 over RAID1 is because if you are working with more than two drives, having a 1:1 redundancy in disks becomes increasingly wasteful and stupid. You only need to protect against one or two drive failures overall, so having 10 disks all in RAID1's means 5 of them are for redundancy, whereas if you use RAID6 then only 2 of them are needed for redundancy and you increase your space by 3 more drives. With RAID6 you can have up to two drives failing and only have to have two of them be redundant, whereas with RAID1 if two linked drives fail you're data is lost.

Anyone having more than two drives needs RAID5 or RAID6 otherwise you're wasting space and are stupid. Unless you absolutely have to have a slightly faster increase of speeds that a RAID1+0 would offer, but you don't need that anymore. RAID5/6 is basically as fast as striped drives and still takes advantage of the fact multiple drives are working together to perform tasks.

I expect RAID5/6 under BTRFS may end up being even faster than md RAID5/6, too, but we shall see.

[pal666]

You love wasting electricity and drive space?

you can't afford fast and reliable storage? then you are cheap moron

[gilboa]

why? raid 1 is faster and more reliable. raid5 is for poor people who have not enough drive space.

1. RAID1 is *not* faster. In many loads (E.g. large sequential read/write) large RAID5 (and 6) array will run circles around RAID1.
E.g. On a server w/ 8 x 4TB 7200RPM drives I have two Linux MD RAIDs.
RAID1 for OS + boot.
RAID6 for data.
The RAID1 large block sequential r/w usually max at ~100MB/s.
The RAID6 large block sequential r/w usually max at ~500MB/s.

2. RAID1 is just as *unreliable* as RAID5 if not more. Both can only survive a single disk failure. Only RAID6 (or above) can be considered semi-safe.
3. No offense intended, but your arrogance blinds you (and your comment is very arrogant). If you need to build a 100+ or 200+ TB RAID, RAID 1 or even 10 is simply not an option. In this case, you either use RAID6 w/ a large number of spares, or use some proprietary RAID format (E.g. ZFS' RAID-Z).

- Gilboa

[gilboa]

you can't afford fast and reliable storage? then you are cheap moron

Care to share the combined RAID space you have?
As you are so keen to call everybody cheap morons, I'd like to know how many TB (or PB) your lordship owns / manages...

- Gilboa

[pgoetz]

why? raid 1 is faster and more reliable. raid5 is for poor people who have not enough drive space.

Sure. I have servers which require 30TB partitions. How exactly are you going to implement that using RAID 1? LVM?