gpart backup | gpart restore does not alway give you exact replication

Today I was setting up some drives for testing.

I did this manually:

root@r730-04:~ # gpart create -s gpt da2
da2 created

root@r730-04:~ # gpart add -t efi -s 260M -a 4k da2
da2p1 added

root@r730-04:~ # gpart add -t freebsd-swap -s 8G -a 4k da2
da2p2 added
root@r730-04:~ # gpart add -t freebsd-zfs -a 4k da2
da2p3 added


root@r730-04:~ # gpart show da2
=>      40  62533216  da2  GPT  (30G)
        40    532480    1  efi  (260M)
    532520  16777216    2  freebsd-swap  (8.0G)
  17309736  45223520    3  freebsd-zfs  (22G)

Now let’s duplicate that over here:

root@r730-04:~ # gpart backup da2 | gpart restore da3
=>      40  62533216  da2  GPT  (30G)
        40    532480    1  efi  (260M)
    532520  16777216    2  freebsd-swap  (8.0G)
  17309736  45223520    3  freebsd-zfs  (22G)

=>      34  62533229  da3  GPT  (30G)
        34         6       - free -  (3.0K)
        40    532480    1  efi  (260M)
    532520  16777216    2  freebsd-swap  (8.0G)
  17309736  45223520    3  freebsd-zfs  (22G)
  62533256         7       - free -  (3.5K)

root@r730-04:~ # 

That’s not the same. However, it is similar to the other drives in this host:

root@r730-04:~ # gpart show da0
=>        34  1953525101  da0  GPT  (932G)
          34           6       - free -  (3.0K)
          40      532480    1  efi  (260M)
      532520        2008       - free -  (1.0M)
      534528    16777216    2  freebsd-swap  (8.0G)
    17311744  1936213384    3  freebsd-zfs  (923G)
  1953525128           7       - free -  (3.5K)

Granted, that’s a different type of drive.

da2 and da3 look like this:

Nov 20 14:13:40 r730-04 kernel: da2 at mrsas0 bus 1 scbus1 target 7 lun 0
Nov 20 14:13:40 r730-04 kernel: da2:  Fixed Direct Access SPC-4 SCSI device
Nov 20 14:13:40 r730-04 kernel: da2: Serial Number 134106402147
Nov 20 14:13:40 r730-04 kernel: da2: 150.000MB/s transfers
Nov 20 14:13:40 r730-04 kernel: da2: 30533MB (62533296 512 byte sectors)

Nov 20 14:13:40 r730-04 kernel: da3 at mrsas0 bus 1 scbus1 target 6 lun 0
Nov 20 14:13:40 r730-04 kernel: da3:  Fixed Direct Access SPC-4 SCSI device
Nov 20 14:13:40 r730-04 kernel: da3: Serial Number 134106400102
Nov 20 14:13:40 r730-04 kernel: da3: 150.000MB/s transfers
Nov 20 14:13:40 r730-04 kernel: da3: 30533MB (62533296 512 byte sectors)

They are the same model, etc.

Going the other way

Let’s destroy da2 and use da3 as a model:

root@r730-04:~ # gpart destroy -F da2
da2 destroyed
root@r730-04:~ # gpart backup da3 | gpart restore da2
root@r730-04:~ # gpart show da2 da3
=>      34  62533229  da2  GPT  (30G)
        34         6       - free -  (3.0K)
        40    532480    1  efi  (260M)
    532520  16777216    2  freebsd-swap  (8.0G)
  17309736  45223520    3  freebsd-zfs  (22G)
  62533256         7       - free -  (3.5K)

=>      34  62533229  da3  GPT  (30G)
        34         6       - free -  (3.0K)
        40    532480    1  efi  (260M)
    532520  16777216    2  freebsd-swap  (8.0G)
  17309736  45223520    3  freebsd-zfs  (22G)
  62533256         7       - free -  (3.5K)

root@r730-04:~ # 

What gives here?

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