>>94
z5zの場合、Project TrebleのSlot A/B機種なので、recoveyはboot partition内に統合されていて、単独のrecovery.imgは存在しない。

https://www.google.com/amp/s/www.xda-developers.com/how-a-b-partitions-and-seamless-updates-affect-custom-development-on-xda/amp/

z5: Slot A only
z5z: Slot A/B

boot: holds the kernel, ramdisk, and on A/B devices also the recovery as well

recovey: holds the recovery, where TWRP is most commonly flashed on A-only devices (A/B devices don’t have a dedicated recovery partition)
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https://android.stackexchange.com/questions/203499/a-b-seamless-update-device-questions
にある様に、

Step1 アップデート前
Slot A: Active PartitionでAndroid8.0
Slot B: Negative ParitionでAndroid8.0

Step2 アップデート実施
Slot A: Active PartitionでAndroid8.0のまま
Slot B: Negative Partitionで8.1にアップデート

ここで、再起動させると

Step 3 再起動後
Slot A:Negative PartitionでAndroid8.0のまま
Slot B:Active Partitionになって8.1となって起動