Summary: After successfully completed btrfs replace start, btrfs fi show lists the old devid size not the new devid size. kernel-3.17.2-300.fc21.x86_64 ##Originally discovered with this kernel btrfs-progs-3.17-1.fc21.x86_64 ##Before devid2 is missing (normal mount of 2x HDDs, raw block devices are formatted, no partitioning) #btrfs fi show /mnt/btrfs1 Label: 'btrfs1' uuid: 0f1c615f-30a0-4166-8a3c-987849551513 Total devices 2 FS bytes used 270.58GiB devid 1 size 465.76GiB used 272.03GiB path /dev/sdc devid 2 size 298.09GiB used 272.03GiB path /dev/sdb ##During btrfs replace start 2 /dev/sdb /mnt/btrfs1; new /dev/sdb is 750GB #btrfs fi show /mnt/btrfs1 Label: 'btrfs1' uuid: 0f1c615f-30a0-4166-8a3c-987849551513 Total devices 4 FS bytes used 270.58GiB devid 0 size 298.09GiB used 272.03GiB path /dev/sdb devid 1 size 465.76GiB used 272.03GiB path /dev/sdc *** Some devices missing ##After btrfs replace completes, and after umount, physically disconnecting/reconnecting, and remounting Label: 'btrfs1' uuid: 0f1c615f-30a0-4166-8a3c-987849551513 Total devices 2 FS bytes used 270.58GiB devid 1 size 465.76GiB used 272.03GiB path /dev/sdc devid 2 size 298.09GiB used 272.03GiB path /dev/sdb devid2/sdb is now the new device (750GB, 698.7GiB as reported by lsblk). The value from btrfs fi show is still the old value and is now wrong. [ 6141.864212] usb 4-2: USB disconnect, device number 5 [ 6141.865378] sd 9:0:0:0: [sdb] Synchronizing SCSI cache [ 6141.865448] sd 9:0:0:0: [sdb] [ 6141.865452] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [ 6145.254144] usb 4-1: new SuperSpeed USB device number 6 using xhci_hcd [ 6145.266077] usb 4-1: New USB device found, idVendor=174c, idProduct=5136 [ 6145.266084] usb 4-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1 [ 6145.266088] usb 4-1: Product: AS2105 [ 6145.266090] usb 4-1: Manufacturer: ASMedia [ 6145.266093] usb 4-1: SerialNumber: 00000000000000000000 [ 6145.266861] usb-storage 4-1:1.0: USB Mass Storage device detected [ 6145.267536] scsi host10: usb-storage 4-1:1.0 [ 6146.271397] scsi 10:0:0:0: Direct-Access ASMT 2105 0 PQ: 0 ANSI: 6 [ 6146.272183] sd 10:0:0:0: Attached scsi generic sg2 type 0 [ 6148.239288] sd 10:0:0:0: [sdb] 1465149168 512-byte logical blocks: (750 GB/698 GiB) [ 6148.239748] sd 10:0:0:0: [sdb] Write Protect is off [ 6148.239755] sd 10:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 6148.240077] sd 10:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 6148.265774] sdb: unknown partition table [ 6148.267153] sd 10:0:0:0: [sdb] Attached SCSI disk # df -h /dev/sdc 382G 271G 27G 92% /mnt/btrfs1 This is incorrect as well, it's the exact same information provided by df before the replace. It seems like btrfs replace is not doing a resize to fill all available space on the specified new block device.
Observed the same issue here with Ubuntu's 3.19.0-12 and tools 3.19.1. I btrfs replace'd dev 8, a 3TB drive, with 4TB and the dev is still showing 3TB. Like you found, btrfs fi resize 8:max /thefs fixed the problem. Thanks for that tip.
(In reply to Dan van der Ster from comment #1) > Observed the same issue here with Ubuntu's 3.19.0-12 and tools 3.19.1. I > btrfs replace'd dev 8, a 3TB drive, with 4TB and the dev is still showing > 3TB. > > Like you found, btrfs fi resize 8:max /thefs fixed the problem. Thanks for > that tip. Yes, this is the current behavior, and it's even documented in the btrfs-replace man page[1]. There is a current effort to add a new flag in order to have this automatically resized after a device replace, but it may take some time until it hits mainline. Thanks