On Saturday 30 January 2010, 0bo0 wrote: > Is the goal NOT to accurately represent the actual available space? > Seems rather odd that users are simply to know/accept that "available > space" in btrfs RAID-10 != "available space" in md RIAD-10 ...
As reported more time in this ML, btrfs is able to store the data in striping/raid1 mode per-file-basis. The space on the disk is grouped in chunk. The raid mode is set per-chunk- basis [1]. So a file stored in a chunk may be written two times (in one or two different disk), and another file stored in another chunk may be written with a different policy. In fact the btrfs store the data in "raid0" mode, and the metadata in raid1 mode, even with only one disk. Even tough the words "raid1/0" are incorrect with only one disk. So key points are: - it is incorrect to say that the btrfs filesystem is configured in raidX mode - it is correct that the file xyz is stored in raidX mode - is quite simple to evaluate the space available. It is more complex to evaluate before the file creation how many of the space available a file of a certain size consumes. - unfortunately, today are not available tools that permits to manage the raid mode of a file BR G.Baroncelli -- gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijack inwind it> Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512 -- 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
