Partition start sector

[srirams]

I'm building my array and converting all my disks to xfs. I'm adding the disks to the array, letting unraid format them (to XFS) and then copying data over (I have no parity yet). For the majority of the disks, the partition starts at sector 64, however for two disks the start sector is 2048 (I beleive these were previously ext4). Is this going to be a problem for when I add parity disks?

 

root@tower:~# gdisk -l /dev/sdd
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdd: 23437770752 sectors, 10.9 TiB
Model: WDC WD120EMAZ-11
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): 1334C70E-9F04-4727-9279-2C9036E38A27
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 23437770718
Partitions will be aligned on 64-sector boundaries
Total free space is 30 sectors (15.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1              64     23437770718   10.9 TiB    8300

root@tower:~# gdisk -l /dev/sdj
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdj: 23437770752 sectors, 10.9 TiB
Model: WDC WD120EDAZ-11
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): C05405D7-6676-4EE3-9C3E-520742D748C9
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 23437770718
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048     23437770718   10.9 TiB    8300  Linux filesystem

 

[JorgeB]

10 hours ago, srirams said:

Is this going to be a problem for when I add parity disks?

No, but it's weird, only non rotational devices should have the partition start on sector 2048, the disks were formatted by Unraad correct? If you didn't reboot yet after formatting please post the diags.

[srirams]

I'm able to reproduce this using a new drive:

 

New drive:

 

root@trantor:~# gdisk -l /dev/sdv
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdv: 23437770752 sectors, 10.9 TiB
Model: WDC WD120EDAZ-11
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): 9FD27D35-A843-4727-A701-4B422479775D
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 23437705182
Partitions will be aligned on 2048-sector boundaries
Total free space is 4029 sectors (2.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048     23437703167   10.9 TiB    0700  Elements

 

Adding this to the array gives me a message about unsupported partition layout.

 

Partitioning and formatting the disk like I used to do using:

 

gdisk /dev/sdv
o -> new gpt
n -> new partition
w -> write to disk

using all defaults

 

gives me:

root@trantor:~# gdisk -l /dev/sdv
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdv: 23437770752 sectors, 10.9 TiB
Model: WDC WD120EDAZ-11
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): 4116A97E-4ECA-4C4A-A0E2-5E2F6C568519
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 23437770718
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048     23437770718   10.9 TiB    8300  Linux filesystem

 

Now, when I try to add this disk to the array, all I get is a message about unsupported filesystem. I then format this in unraid, and the start sector is kept at 2048.

 

root@trantor:~# gdisk -l /dev/sdv
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdv: 23437770752 sectors, 10.9 TiB
Model: WDC WD120EDAZ-11
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): 4116A97E-4ECA-4C4A-A0E2-5E2F6C568519
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 23437770718
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048     23437770718   10.9 TiB    8300  Linux filesystem
root@trantor:~# xfs_info /dev/sdv1
meta-data=/dev/sdv1              isize=512    agcount=11, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=2929721083, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

 

trantor-diagnostics-20210327-1001.zip

[WizADSL]

Try:

You can try using sfdisk to copy the partition table from one drive to another.  I have not tested this personally but it's worth a try although I would make sure you don't have irreplaceable data on the subject disk as I assume this will nuke it.  In the command below "sfdisk --dump" will dump the partition table layout of /dev/sdd in a format that the following command (through the pipe) can then write the same layout to /dev/sdv.  If you examine the output of the --dump command you can see what will be done and you could proabaly do it "manually" if you prefer.

 

sfdisk --dump /dev/sdd | sfdisk --force /dev/sdv

 

[JorgeB]

17 hours ago, srirams said:

Adding this to the array gives me a message about unsupported partition layout.

Are you formatting the disks before adding to the array?

[srirams]

18 hours ago, WizADSL said:

You can try using sfdisk to copy the partition table from one drive to another.

 

Thanks, although if it's not going to be a problem, I think I will leave it be.

 

3 hours ago, JorgeB said:

Are you formatting the disks before adding to the array?

 

Yes, sorry, I left out that I formatted with ext4 before adding to the array.

[JorgeB]

20 minutes ago, srirams said:

Yes, sorry, I left out that I formatted with ext4 before adding to the array.

Unraid should still wipe the disk and reformat it with the correct starting sector, 2048 starting sector won't cause issues with parity, but it might cause mounting issues in the future, also if you try to replace a disk with the standard 64 sector with one of the same size with a 2048 starting sector it won't be possible, due to the partition being smaller, so to avoid any future issues I would recommend wiping those disks and letting Unraid format them.