Am Mittwoch, 27. August 2014, 10:54:56 schrieb Chris Murphy: > On Aug 27, 2014, at 5:45 AM, Martin Steigerwald <mar...@lichtvoll.de> wrote: > > Hi! > > > > Now I get this with 3.17-rc2: > > > > merkaba:~> LANG=C df -hT / /home > > Filesystem Type Size Used Avail Use% Mounted on > > /dev/dm-5 btrfs 30G 17G 23G 43% / > > /dev/dm-0 btrfs 160G 129G 59G 69% /home > > > > > > /: 17+23 = 40 GiB, compressed 10 GiB away with lzo? > > /home: 59+129 = 188 GiB, compressed 28 GiB away with lzo? > > > > > > This is BTRFS RAID 1 on Dual SSD: > > > > merkaba:~> btrfs fi df / > > Data, RAID1: total=25.00GiB, used=15.33GiB > > System, RAID1: total=8.00MiB, used=16.00KiB > > Metadata, RAID1: total=2.00GiB, used=677.33MiB > > unknown, single: total=240.00MiB, used=0.00 > > > > merkaba:~> btrfs fi df /home > > Data, RAID1: total=154.97GiB, used=125.70GiB > > System, RAID1: total=32.00MiB, used=48.00KiB > > Metadata, RAID1: total=5.00GiB, used=2.71GiB > > unknown, single: total=512.00MiB, used=0.00 > > Hmm, I'm not seeing such a large discrepancy between Used+Avail and Size.
I see. Well the /home has a large maildir and lots of git checkouts with highly compressible text files. My data directory for larger files which is only on the mSATA SSD doesn´t have this discrepancy: merkaba:~> LANG=C df -hT /daten Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/msata-daten btrfs 200G 183G 17G 92% /daten merkaba:~> btrfs fi df /daten Data, single: total=187.01GiB, used=182.05GiB System, single: total=4.00MiB, used=48.00KiB Metadata, single: total=1.01GiB, used=288.09MiB unknown, single: total=112.00MiB, used=0.00 I also use compress=lzo on it, although it I wonder whether its necessary as I think the Crucial m500 mSATA SSD firmware compresses itself while the Intel SSD 320 SATA SSD firmware does not. But still even with compression in the firmware, it BTRFS compresses I can use more of the capacity. I wonder whether this can harm the reliability of the SSD, if its firmware relies on at least partly compressible data. > No compression, all volumes populated with send/receive and contain same > data. Well I wouldn´t expect to see discrepancies without compressed data. But on the other hand I did not dig into how the new calculation actually works so far. > 3.16.1 > # df -h > Filesystem Size Used Avail Use% Mounted on > /dev/sdb 40G 2.8G 37G 7% /home # single 40GB > device /dev/sdc 40G 5.5G 33G 15% /mnt # two 20GB > devices, raid1 > > Reboot 3.17.0rc2 > # df -h > Filesystem Size Used Avail Use% Mounted on > /dev/sdb 40G 2.8G 37G 7% /home # single 40GB > device /dev/sdc 20G 2.8G 17G 15% /mnt # two 20GB > devices, raid1 > > ====== > sde is two 20GB devices, raid1, -o compress, populated the same as above w/ > send/receive > > 3.16.1 > Filesystem Size Used Avail Use% Mounted on > /dev/sde 40G 3.8G 35G 10% /mnt > > 3.17.0rc2 > Filesystem Size Used Avail Use% Mounted on > /dev/sde 20G 2.0G 18G 10% /mnt > > > In the last example, Used went from 2.8G to 2.0G due to compression. But > with or without compression, Used+Avail=Size. Hmmm, I see. Then it might not be compression at all what explains the differences I see? Any other explainations? Ciao, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- 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
