/system wipe slot?

[DevADX]

When one wipes the /system partition from TWRP, does it only wipe the current slot? If so, what would be the point to wipe system prior to flashing a new ROM as it installs to the other slot?

If the above is true, what would be the correct steps to actually wipe the target /system? Thanks.

 

[Pain-N-Panic]

Why not just wipe both slots to be safe? Then install the ROM to both slots as well.

 

[DevADX]

Why not just wipe both slots to be safe? Then install the ROM to both slots as well.

Installing it to both slots would mean installing it 3 times though:
Wipe system in slot A
Install to slot B (system not wiped)
Reboot to slot B
Wipe system in slot B
Install to slot A
Reboot to slot A
Install to slot B

Wouldn't it be easier to just wipe the target system since it always installs to the opposite slot?

 

[Pain-N-Panic]

Or you could wipe slot A, boot to slot B, wipe slot B. Flash ROM in B, boot to slot A and flash again (flashing to B.)

Ive read on here having a custom ROM flashed to only one slot can lead to issues. I don't know how true that is. Even when I flash the factory images I wipe both slots before using the flash all script (which flashes to both slots.)

 

[noidea24]

yall are crazy.
i just wipe and flush (lol, get it? wipe and flush/flash??) anyways.
yeah, i boot to twrp, wipe, flash, and reboot. i have never had problems with the phone booting to the opposing slot, and if it ever does ill just boot twrp and change active slots.

 

[Golf c]

I think the guy above has it right.
The factory image does not flash to both slots. The non bootable system_other.img is the only thing that gets flashed to the inactive system partition. The vendor, boot, bootloader, radio etc... Does not get flashed to the inactive slot with a flash-all.
All custom roms get flashed to the inactive system and boot partitions when flashed in TWRP. So if you don't wipe the current active system partition before flashing a custom rom, you can end up with a custom rom in one slot and a different rom in the other slot. Force closing apps and problems with the one shared data partition.
The beauty of this slot thing is there are many ways to flash things. You can switch slots before you flash and always keep the same slot. Some people do that.
Custom roms wipe the inactive system partition they are being flashed too. So no need to worry about that.
The best thing to do is to know exactly what is in each slot at all times.