BTRFS SSD RAID 1: Does it trim on both devices? :)
Hi!
Since a few days this ThinkPad T520 has 780 GB SSD capacity. The 300 GB of the Intel SSD 320 were almost full and that 480 GB Crucial m500 mSATA SSD was cheap enough to just buy it.
I created a new logical volume for big and not that often changed files that is just on the msata and moved all the music and photo files to it.
Then I thought I´d work in place, just shrink the /home volume on the Intel SSD 320 and then add a similar sized volume on the Crucial and have it rebalanced to metadata and data RAID 1. Unfortunately the shrinking hung at some time. I didn´t check with a scrub afterward, but I rsync´d all data to a newly created volume on the Crucial and then rebalanced the other way around. Since the rsync didn´t show any I/O errors I suppose the BTRFS with the shrink failure was still okay. I report this shrink failure separately.
So now I have a BTRFS RAID 1 for /home and / and I wondered: Does BTRFS trim on all devices on issuing fstrim?
Some details:
merkaba:~> btrfs fi show
Label: debian uuid: […]
Total devices 2 FS bytes used 15.89GiB
devid 1 size 30.00GiB used 19.03GiB path /dev/mapper/sata-debian
devid 2 size 30.00GiB used 19.01GiB path /dev/dm-2
Label: home uuid: […]
Total devices 2 FS bytes used 91.59GiB
devid 1 size 150.00GiB used 102.00GiB path /dev/dm-0
devid 2 size 150.00GiB used 102.00GiB path /dev/mapper/sata-homeLabel: daten uuid: […]
Total devices 1 FS bytes used 148.36GiB
devid 1 size 200.00GiB used 150.02GiB path /dev/mapper/msata-daten
merkaba:~> LANG=C df -hT -t btrfs
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/sata-debian btrfs 60G 32G 26G 56% / /dev/dm-0 btrfs 300G 184G 113G 62% /home /dev/mapper/sata-debian btrfs 60G 32G 26G 56% /mnt/debian-zeit /dev/dm-0 btrfs 300G 184G 113G 62% /mnt/home-zeit /dev/mapper/msata-daten btrfs 200G 149G 51G 75% /daten
(the "zeit" mounts show the root sub volume for snapshots)
merkaba:[…]> ./btrfs fi df /
Disk size: 60.00GB Disk allocated: 38.04GB Disk unallocated: 21.96GB Used: 15.89GB Free (Estimated): 14.13GB (Max: 25.10GB, min: 14.12GB) Data to disk ratio: 50 % merkaba:[…]> ./btrfs fi df /home Disk size: 300.00GB Disk allocated: 204.00GB Disk unallocated: 96.00GB Used: 91.59GB Free (Estimated): 58.41GB (Max: 106.41GB, min: 58.41GB) Data to disk ratio: 50 %
merkaba:[…]> ./btrfs device disk-usage //dev/dm-2 30.00GB
Data,RAID1: 17.00GB
Metadata,RAID1: 2.00GB
System,RAID1: 8.00MB
Unallocated: 10.99GB
/dev/mapper/sata-debian 30.00GB
Data,Single: 8.00MB
Data,RAID1: 17.00GB
Metadata,Single: 8.00MB Metadata,RAID1: 2.00GB System,Single: 4.00MB System,RAID1: 8.00MB
Unallocated: 10.97GB
merkaba:[…]> ./btrfs filesystem disk-usage -t /
Data Data Metadata Metadata System System
Single RAID1 Single RAID1 Single RAID1 Unallocated
/dev/dm-2 - 17.00GB - 2.00GB - 8.00MB 10.99GB
/dev/mapper/sata-debian 8.00MB 17.00GB 8.00MB 2.00GB 4.00MB 8.00MB 10.97GB
====== ======= ======== ======== ====== ======= ===========Total 8.00MB 17.00GB 8.00MB 2.00GB 4.00MB 8.00MB 21.96GB
Used 0.00 15.13GB 0.00 778.00MB 0.00 16.00KB
merkaba:[…]> ./btrfs device disk-usage /home/dev/dm-0 150.00GB
Data,RAID1: 98.00GB
Metadata,RAID1: 4.00GB
System,Single: 4.00MB
Unallocated: 48.00GB
/dev/mapper/sata-home 150.00GB
Data,RAID1: 98.00GB
Metadata,RAID1: 4.00GB
Unallocated: 48.00GB
merkaba:[…]> ./btrfs filesystem disk-usage -t /home
Data Metadata System
RAID1 RAID1 Single Unallocated
/dev/dm-0 98.00GB 4.00GB 4.00MB 48.00GB
/dev/mapper/sata-home 98.00GB 4.00GB - 48.00GB
======= ======== ======= ===========
Total 98.00GB 4.00GB 4.00MB 96.00GB
Used 89.60GB 1.99GB 16.00KBAnd some healthly over prosioning:
merkaba:~> vgs
VG #PV #LV #SN Attr VSize VFree
msata 1 3 0 wz--n- 446,64g 66,64g sata 1 3 0 wz--n- 278,99g 86,99g
Thanks,
Signature · 2 lines
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7