On Wed, Dec 10, 2014 at 9:21 PM, Duncan <1i5t5.dun...@cox.net> wrote: > Robert White posted on Wed, 10 Dec 2014 02:53:40 -0800 as excerpted: > >> On 12/09/2014 05:08 PM, Dongsheng Yang wrote: >>> On 12/10/2014 02:47 AM, Goffredo Baroncelli wrote: >>>> Hi Dongsheng On 12/09/2014 12:20 PM, Dongsheng Yang wrote: >>>>> When function btrfs_statfs() calculate the tatol size of fs, it is >>>>> calculating the total size of disks and then dividing it by a factor. >>>>> But in some usecase, the result is not good to user. >>>>> >>>>> Example: >>>>> # mkfs.btrfs -f /dev/vdf1 /dev/vdf2 -d raid1 >>>>> # mount /dev/vdf1 /mnt >>>>> # dd if=/dev/zero of=/mnt/zero bs=1M count=1000 >>>>> # df -h /mnt >>>>> Filesystem Size Used Avail Use% Mounted on >>>>> /dev/vdf1 3.0G 1018M 1.3G 45% /mnt >>>>> >>>>> # btrfs fi show /dev/vdf1 >>>>> Label: none uuid: f85d93dc-81f4-445d-91e5-6a5cd9563294 >>>>> Total devices 2 FS bytes used 1001.53MiB >>>>> devid 1 size 2.00GiB used 1.85GiB path /dev/vdf1 >>>>> devid 2 size 4.00GiB used 1.83GiB path /dev/vdf2 >>>>> >>>>> a. df -h should report Size as 2GiB rather than as 3GiB. >>>>> Because this is 2 device raid1, the limiting factor is devid 1 @2GiB. >>>> I agree >> >> NOPE. >> >> The model you propose is too simple. >> >> While the data portion of the file system is set to RAID1 the metadata >> portion of the filesystem is still set to the default of DUP. > > Metadata defaults to DUP only on a single-device filesystem. On a multi- > device filesystem, metadata defaults to raid1. (FWIW, for both, data > defaults to single.)
Exactly. Thanx for your clarification. :) > > And in the example, the mkfs was supplied with two devices, so there's no > dup metadata remaining from a formerly single-device filesystem, either. > (Tho there will be the small single-mode stubs, empty, remaining from the > mkfs process, as no balance has been run to delete them yet, but those > are much smaller and empty.) Yes. One question not related here: how about delete them in the end of mkfs? Thanx > > -- > Duncan - List replies preferred. No HTML msgs. > "Every nonfree program has a lord, a master -- > and if you use the program, he is your master." Richard Stallman > > -- > 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 -- 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
