Solved Doubt about slices/partitions


Active Member

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Is "slice" only related to MBR scheme?

When is it necessary/recommend to use bsdlabel?
I mean, I installed (with bsdinstall) FreeBSD on different machines (each time with GPT scheme), I never found any label information:

# bsdlabel -A da0

bsdlabel: /dev/da0: no valid label found
Thank you


Son of Beastie

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Is "slice" only related to MBR scheme?

You can have either disk labels or partition labels.
Take a good look at Warrens disk page. It really is a definitive guide for disk usage.

glabel is a tool for labeling drives.

root@Inventec:~ # glabel status
                                      Name  Status  Components
gptid/0767f8fd-db48-11e8-a961-008cfacbad48     N/A  ada0p1
                     label/S0L00RTT0000932     N/A  da0
                     label/S0L00S1D0000932     N/A  da1
                     label/S0L00QG70000932     N/A  da2
                     label/S0L00QQ90000932     N/A  da3
                     label/S0L0102C0000932     N/A  da4
Here you can see that I have used glabel on my raid3 drives using the serial number as the label.

It also changes where you attach to the drives.
root@Inventec:~ # ls /dev/label
S0L00QG70000932    S0L00QQ90000932    S0L00RTT0000932    S0L00S1D0000932    S0L0102C0000932
Instead of /dev/da0 or /dev/da1 I now I use /dev/label/<drive serial number>

The reason I use the serial number is I have a hotswap drive bays. When FreeBSD boots the drives come up in different order.
So da0 could be da4 on the next boot wrecking any arrays I have created. So I use disk labels instead.

To find my drives serial numbers:
root@Inventec:~ # camcontrol inquiry da0
pass2: <SEAGATE ST450MM0026 0001> Fixed Direct Access SPC-4 SCSI device
pass2: Serial Number S0L00RTT00009320PMBN
pass2: 600.000MB/s transfers, Command Queueing Enabled


Son of Beastie

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Messages: 3,499

I had to delete a blurb I wrote about bsdlabel. It was wrong. If using GPT you can ignore bsdlabel.
MBR doesn't support over 2 Terrabyte drives and using slices is way more confusing than the p1, p2 arrangement GPT uses.
The only caveat is that GPT requires a seperate boot partition. That is the only negative I can find.
Good read on all things disk.