[HTC Sensation] RayeR:
I could't because TWRP restarts itself... Before it messed I could mount /system and /cache but not /data.

Fortunatelly I was able to bring TWRP back working. I tried to flash limited RRU zip from SD card owerwriting some parts except date because it hanged on it. After this I still cannot boot system (only HTC logo) but TWRP works now.

I found emmc-scan utility on this forum and run on all devices/partition but it didn't found any error. It seems to scan only short data blocks 1M aligned so if error is between it's misssed. From dmesg log I can see bad sectors in cache, data and log partitions:

dmesg |grep I/O
<3>[ 672.744476] end_request: I/O error, dev mmcblk0, sector 4709845
<3>[ 672.744842] Buffer I/O error on device mmcblk0p28, logical block 4352
<3>[ 672.773071] end_request: I/O error, dev mmcblk0, sector 4711893
<3>[ 672.773254] Buffer I/O error on device mmcblk0p28, logical block 4608
<3>[ 672.801452] end_request: I/O error, dev mmcblk0, sector 4713941
<3>[ 672.801544] Buffer I/O error on device mmcblk0p28, logical block 4864
<3>[ 776.400177] end_request: I/O error, dev mmcblk0, sector 4412899
<3>[ 776.400268] Buffer I/O error on device mmcblk0p24, logical block 0
<3>[ 776.400543] end_request: I/O error, dev mmcblk0, sector 4412901
<3>[ 776.400665] Buffer I/O error on device mmcblk0p24, logical block 1
<3>[ 776.400848] end_request: I/O error, dev mmcblk0, sector 4412903
<3>[ 776.400939] Buffer I/O error on device mmcblk0p24, logical block 2
<3>[ 776.401123] end_request: I/O error, dev mmcblk0, sector 4412905
<3>[ 776.401214] Buffer I/O error on device mmcblk0p24, logical block 3
<3>[ 776.401397] end_request: I/O error, dev mmcblk0, sector 4412907
<3>[ 776.401489] Buffer I/O error on device mmcblk0p24, logical block 4
<3>[ 776.401672] end_request: I/O error, dev mmcblk0, sector 4412909
<3>[ 776.401763] Buffer I/O error on device mmcblk0p24, logical block 5
<3>[ 776.401947] end_request: I/O error, dev mmcblk0, sector 4412911
<3>[ 776.402130] Buffer I/O error on device mmcblk0p24, logical block 6
<3>[ 776.402221] end_request: I/O error, dev mmcblk0, sector 4412913
<3>[ 776.402404] Buffer I/O error on device mmcblk0p24, logical block 7
<3>[ 776.402526] end_request: I/O error, dev mmcblk0, sector 4412915
<3>[ 776.402679] Buffer I/O error on device mmcblk0p24, logical block 8
<3>[ 776.402801] end_request: I/O error, dev mmcblk0, sector 4412917
<3>[ 776.402984] Buffer I/O error on device mmcblk0p24, logical block 9
<3>[ 783.229522] end_request: I/O error, dev mmcblk0, sector 1966080
<3>[ 783.229736] Buffer I/O error on device mmcblk0p23, logical block 0
<3>[ 783.229919] end_request: I/O error, dev mmcblk0, sector 1966082
<3>[ 783.230102] Buffer I/O error on device mmcblk0p23, logical block 1
<3>[ 783.230194] end_request: I/O error, dev mmcblk0, sector 1966084
<3>[ 783.230377] Buffer I/O error on device mmcblk0p23, logical block 2
<3>[ 783.230590] end_request: I/O error, dev mmcblk0, sector 1966086
<3>[ 783.230773] Buffer I/O error on device mmcblk0p23, logical block 3
<3>[ 783.230865] end_request: I/O error, dev mmcblk0, sector 1966088
<3>[ 783.231048] Buffer I/O error on device mmcblk0p23, logical block 4
<3>[ 783.231140] end_request: I/O error, dev mmcblk0, sector 1966090
<3>[ 783.231323] Buffer I/O error on device mmcblk0p23, logical block 5
<3>[ 783.231414] end_request: I/O error, dev mmcblk0, sector 1966092
<3>[ 783.231597] Buffer I/O error on device mmcblk0p23, logical block 6
<3>[ 783.231719] end_request: I/O error, dev mmcblk0, sector 1966094
<3>[ 783.231903] Buffer I/O error on device mmcblk0p23, logical block 7
<3>[ 783.232055] end_request: I/O error, dev mmcblk0, sector 1966096
<3>[ 783.232177] Buffer I/O error on device mmcblk0p23, logical block 8
<3>[ 783.232330] end_request: I/O error, dev mmcblk0, sector 1966098
<3>[ 783.232452] Buffer I/O error on device mmcblk0p23, logical block 9

Maybe it would be possible to repartition it loaving some empty space and avoid this bad sectors. TRWP allows resize filesystem in advanced wipe - failed ERROR: 4

Now I can mount all partitions in TWRP before doing some action but wipe of /data fails and then cannot longer mount it. I can reformat it to F2FS without error and then it can be mounted but I don't know what CM ROM supports this FS. CM12 from 8.3.2016 doesn't boot. I still hope it could be possible to put /data on external sd card but it would require some CM ROM modification that I currently have no knowledges how to do it....