On a system running the Debian 3.14.15-2 kernel I added a new drive to a RAID-1 array. My aim was to add a device and remove one of the old devices. Sep 21 11:26:51 server kernel: [2070145.375221] BTRFS: lost page write due to I/O error on /dev/sdc3 Sep 21 11:26:51 server kernel: [2070145.375225] BTRFS: bdev /dev/sdc3 errs: wr 269, rd 0, flush 0, corrupt 0, gen 0 Sep 21 11:27:21 server kernel: [2070175.517691] BTRFS: lost page write due to I/O error on /dev/sdc3 Sep 21 11:27:21 server kernel: [2070175.517699] BTRFS: bdev /dev/sdc3 errs: wr 270, rd 0, flush 0, corrupt 0, gen 0 Sep 21 11:27:21 server kernel: [2070175.517712] BTRFS: lost page write due to I/O error on /dev/sdc3 Sep 21 11:27:21 server kernel: [2070175.517715] BTRFS: bdev /dev/sdc3 errs: wr 271, rd 0, flush 0, corrupt 0, gen 0 Sep 21 11:27:51 server kernel: [2070205.665947] BTRFS: lost page write due to I/O error on /dev/sdc3 Sep 21 11:27:51 server kernel: [2070205.665955] BTRFS: bdev /dev/sdc3 errs: wr 272, rd 0, flush 0, corrupt 0, gen 0 Sep 21 11:27:51 server kernel: [2070205.665967] BTRFS: lost page write due to I/O error on /dev/sdc3 Sep 21 11:27:51 server kernel: [2070205.665971] BTRFS: bdev /dev/sdc3 errs: wr 273, rd 0, flush 0, corrupt 0, gen 0 Anyway the new drive turned out to have some errors, writes failed and I've got a heap of errors such as the above. The errors started immediately after adding the drive and the system wasn't actively writing to the filesystem. So very few (if any) writes made it to the device. # btrfs device delete /dev/sdc3 / ERROR: error removing the device '/dev/sdc3' - Invalid argument It seems that I can't remove the device because removing requires writing. # btrfs device delete /dev/sdc3 / ERROR: error removing the device '/dev/sdc3' - No such file or directory # btrfs device stats / [/dev/sda3].write_io_errs 0 [/dev/sda3].read_io_errs 0 [/dev/sda3].flush_io_errs 0 [/dev/sda3].corruption_errs 57 [/dev/sda3].generation_errs 0 [/dev/sdb3].write_io_errs 0 [/dev/sdb3].read_io_errs 0 [/dev/sdb3].flush_io_errs 0 [/dev/sdb3].corruption_errs 0 [/dev/sdb3].generation_errs 0 [/dev/sdc3].write_io_errs 267 [/dev/sdc3].read_io_errs 0 [/dev/sdc3].flush_io_errs 0 [/dev/sdc3].corruption_errs 0 [/dev/sdc3].generation_errs 0 The drive is attached by USB so I turned off the USB device and then got the above result. So it still seems impossible to remove the device even though it's physically not present. I've connected a new USB disk which is now /dev/sdd, so it seems that BTRFS is keeping the name /dev/sdc locked. Should there be a way to fix this without rebooting or anything? Also as an aside, while the stats about write errors are useful, in this case it would be really good if there was a count of successful writes, it would be useful to know if the successful write count was close to 0. My understanding of the BTRFS design is that there would be no performance penalty for adding counts of the number of successful reads and writes to the superblock. Could this be done? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
