On Thursday 10 of May 2012 21:15:30 Hugo Mills wrote: > On Thu, May 10, 2012 at 09:43:58PM +0200, Hubert Kario wrote: > > On Thursday 10 of May 2012 12:40:49 Martin Steigerwald wrote: > > > Am Mittwoch, 9. Mai 2012 schrieb Kaspar Schleiser: > > > > Hi, > > > > > > > > On 05/08/2012 10:56 PM, Roman Mamedov wrote: > > > > > Regarding btrfs, AFAIK even "btrfs -d single" suggested above > > > > > works > > > > > not "per file", but per allocation extent, so in case of one disk > > > > > failure you will lose random *parts* (extents) of random files, > > > > > which in effect could mean no file in your whole file system will > > > > > remain undamaged. > > > > > > > > Maybe we should evaluate the possiblility of such a "one file gets > > > > on > > > > one disk" feature. > > > > > > > > Helmut Hullen has the use case: Many disks, totally non-critical but > > > > nice-to-have data. If one disk dies, some *files* should lost, not > > > > some > > > > *random parts of all files*. > > > > > > > > This could be accomplished by some userspace-tool that moves stuff > > > > around, combined with "file pinning"-support, that lets the user > > > > make > > > > sure a specific file is on a specific disk. > > > > > > Yeah, basically I think thats the whole point Helmut is trying to > > > make. > > > > > > I am not sure whether that should be in userspace. It could be just an > > > allocation mode like "raid0" or "single". Such as "single" as in one > > > file > > > is really on one disk and thats it. > > > > I was thinking that "linear" would be good name for old style allocator. > > Please do distinguish between the replication level (e.g. "single", > "RAID-1") and the allocator algorithm. These are distinct. Also, note > that both of those work on the scale of chunks/block groups. There is > a further consideration, which is the allocation of file data to block > groups, which is a whole different thing again (and not something I > know a great deal about), but which will also affect the desired > outcome quite a lot.
Yes, I know about that. I was more thinking on the line "how quickly restore aviability of old allocator". Regards, -- Hubert Kario QBS - Quality Business Software 02-656 Warszawa, ul. Ksawerów 30/85 tel. +48 (22) 646-61-51, 646-74-24 www.qbs.com.pl -- 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
