Can I rollback my system with Pre&post type snapshot?

I have OpenSuse 15.3 installed on BTRFS, some day after power failure, I want to rollback my whole system before the date of power failure, with Pre&post type snapshot, because no Single type snapshot were made and list in YaST2-Snapper. There a lot Pre&Post, I view the change of Pre&post type snapshot by YaST2-Snapper, nothing. So some changes to my system after rollback to Pre&post snapshot with snapper rollback commandline will also be removed?

Hi genor and welcome to this forum!

I’m not totally sure if I understand your question but I assume there may be a misunderstanding. First of all, snapper normally always takes two snapshots. (At least in my configuration which I have not changed since install.) In YaST they are listed as “pre&post” but in fact it is two: one “pre” before a certain trigger event and one “post” after it. With snapper in terminal it looks less misleading:

**~ #** snapper list 
    # | Type   | Pre # | Date                     | User | Used Space | Cleanup | Description           | Userdata      
------+--------+-------+--------------------------+------+------------+---------+-----------------------+-------------- 
   0  | single |       |                          | root |            |         | current               |               
 662* | single |       | Mon Jan 18 17:14:56 2021 | root | 308.60 MiB |         | writable copy of #654 |               
1773  | pre    |       | Wed Nov 17 21:33:07 2021 | root | 440.38 MiB | number  | zypp(zypper)          | important=yes 
1774  | post   |  1773 | Wed Nov 17 21:33:31 2021 | root |  37.86 MiB | number  |                       | important=yes 
1783  | pre    |       | Thu Nov 25 22:30:31 2021 | root |  14.10 MiB | number  | zypp(zypper)          | important=yes 
1784  | post   |  1783 | Thu Nov 25 22:32:23 2021 | root |  40.49 MiB | number  |                       | important=yes 
1787  | pre    |       | Fri Nov 26 10:57:14 2021 | root | 752.00 KiB | number  | zypp(zypper)          | important=yes 
1788  | post   |  1787 | Fri Nov 26 10:57:35 2021 | root |  27.07 MiB | number  |                       | important=yes 
1789  | pre    |       | Sat Nov 27 20:19:41 2021 | root |  10.72 MiB | number  | zypp(zypper)          | important=yes 
1790  | post   |  1789 | Sat Nov 27 20:20:42 2021 | root |   3.64 MiB | number  |                       | important=yes 
1791  | pre    |       | Sat Nov 27 20:23:07 2021 | root | 496.00 KiB | number  | yast sw_single        |               
1792  | post   |  1791 | Sat Nov 27 21:29:08 2021 | root |   2.52 MiB | number  |                       |               
1793  | pre    |       | Mon Nov 29 21:47:45 2021 | root |   5.33 MiB | number  | yast sw_single        |               
1794  | post   |  1793 | Mon Nov 29 23:18:05 2021 | root |  96.00 KiB | number  |                       |               
1795  | pre    |       | Mon Nov 29 23:18:39 2021 | root | 176.00 KiB | number  | zypp(zypper)          | important=yes 
1796  | post   |  1795 | Mon Nov 29 23:19:18 2021 | root |  15.04 MiB | number  |                       | important=yes 
1801  | pre    |       | Fri Dec  3 21:32:16 2021 | root |   6.44 MiB | number  | zypp(zypper)          | important=no  
1802  | post   |  1801 | Fri Dec  3 21:34:23 2021 | root |   7.94 MiB | number  |                       | important=no 

The column “description” shows the event that invoked the snapshot. Usually it’s some package transaction. That helps you to select the best snapshot to rollback to. For example if you know your the exact date and time of your blackout and everything was fine at that time then choose the latest “post” snapshot prior to the event. If you choose a “pre” you will roll back to a point before some package action prior to the event.
You may also check out:

man snapper

This might help you
https://doc.opensuse.org/documentation/leap/archive/15.0/reference/html/book.opensuse.reference/cha.snapper.html#sec.snapper.snapshot-boot