Hallo, cwillu, Du meintest am 05.12.10:
>> Maybe you're right. But if you're right then I have got the worst of >> two worlds. I don't want neither RAID0 nor RAID1, I want a bundle of >> different disks (at least partititions) which seem to be one large >> disk. And I've hoped btrfs does this job. > That's what raid0 is, and it's actually the best of both worlds: > your metadata (which will be less than 5% of the data) is safely > duplicated, such that you always have the checksums even with a disk > gone, so you can verify that the data that you still have is good, > while not wasting space duplicating every little bit of file data, > which you may not care about that much, and which you have backed up > anyway (right? right?). Is it really RAID0, or is the btrfs way only similar to RAID0? I don't like RAID0 because I never now on which physical disk the files are. That makes changing disks very risky. [...] > This will almost certainly become much more tunable in the future, > but not every feature that people want is done yet. In fact, most of > the really cool user-visible features aren't done yet. Btrfs is > still pretty young. But I still hope btrfs is smarter than RAID0 or LVM ... [...] >> 1.5 TByte disk: >> btrfs device delete /dev/sdc3 /srv/MM >> btrfs filesystem balance /srv/MM >> >> and then disconnect the 1.5 TByte disk (and hope that now the 2 >> TByte disk sets the limits). >> No nice way ... > No, just run the balance without adding another disk. That will > probably work (although it _will_ take a while on a large > filesystem). I'll try - perhaps it helps for some (few) weeks. > I'm not sure that you understand how this all works though; you > might want to re-read the wiki articles (which I believe have been > freshened up recently). Beg your pardon - my major interest is that the system works. I'm glad when I believe to understand what happens, but this feeling is an add- on, no must. >> Is there a way to avoid this (presumably) RAID mismatch? > Yes, you can specify the raid level for each when you make the > filesystem (and will eventually be able to do it with existing > filesystems). However, as I described above, you really want > metadata to be duplicated. Your problem is more of an unfortunate > case of everything not being tuned quite right yet. May be - I thought avoiding the "RAID0" definition was a good idea. >> By the way: working with TByte disks includes (for home users) that >> there's no backup ... > Not sure why you'd think that. It can't be the bandwidth, and if you > can't afford a second drive, there's a good case to be made that you > can't afford the data you can't afford to lose. The data isn't really valuable - DVB videos. Most of them are copied to disks in a machine about 250 km away. And the TV stations repeat them on and on. Viele Gruesse! Helmut -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
