I've tried by best to search for the answer for this, but there was too much noise -- in pretty much all the discussions on checksum errors and replacing drives, people are asking about replacing a drive after seeing checksum errors. I'm hoping somebody here would be able to help me understand this.
One of my pools experienced two hard drive failures (fortunately from two different vdevs). I've replaced the hard drive, but I've been seeing CKSUM errors popping up on the device that's being replaced. Here's a dump of "zpool status" on my machine:
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scrub: resilver in progress for 0h1m, 0.02% done, 107h55m to go
NAME STATE READ WRITE CKSUM
archivepool DEGRADED 0 0 0
raidz1-0 DEGRADED 0 0 0
replacing-0 DEGRADED 0 0 277
6312875129823442296 UNAVAIL 0 0 0 was /dev/disk/by-id/usb-WD_Ext_HDD_1021_574D415A4132393938343534-0:0
disk/by-id/usb-Seagate_Backup+_Desk_NA5KKM31-0:0 ONLINE 0 0 0
disk/by-id/usb-WD_Ext_HDD_1021_5743415A4132353337343532-0:0 ONLINE 0 0 0
disk/by-id/usb-WD_Ext_HDD_1021_5743415A4133343235393936-0:0 ONLINE 0 0 0
disk/by-id/usb-WD_Ext_HDD_1021_5743415A4133323837353135-0:0 ONLINE 0 0 0
raidz1-1 DEGRADED 0 0 0
disk/by-id/usb-BUFFALO_External_HDD_01092000209C-0:0 ONLINE 0 0 0
disk/by-id/usb-BUFFALO_HD-CXU2_0010100702091C720-0:0 ONLINE 0 0 0
disk/by-id/usb-BUFFALO_HD-CXU2_00101007020C94C80-0:0 ONLINE 0 0 0
replacing-3 DEGRADED 0 0 132
4051679456373771497 UNAVAIL 0 0 0 was /dev/disk/by-id/usb-BUFFALO_HD-CXU2_0010100702071DD80-0:0
disk/by-id/usb-Seagate_Backup+_Desk_NA5KKM3P-0:0 ONLINE 0 0 0
errors: No known data errors
As you can see, the pool is resilvering, but I'm seeing checksum errors on replacing-0 and replacing-3. I understand what checksum errors on the pool, vdev, or device means, but what does it mean on a drive that isn't even a part of the vdev yet? Is my new drive bad, or did I just loose data?