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Re: RAID b/w GPT and NON GPT partition.



On 01/07/15 03:24 PM, Don Armstrong wrote:
On Wed, 01 Jul 2015, Gary Dale wrote:
The size of the RAID array is set by the smallest partition so if you
want to be able to boot from either drive, then putting the ef02
partition in the free space on the new drive means that you will
either not be able to boot from the old drive should the new drive
fail, or you will have different partition tables on each drive.
This is precisely why you should have the EF02 partition on every single
drive in the raid set and run grub-install on all of them (or at the
very least, one more than the number of drives that can fail and still
assemble the array).

You missed the point that this would require different partition tables on the two drives. Moreover, if you ever replaced the original drive with a larger one, you would have to install LVM to get around the ef02 partition - an added layer of complexity that you shouldn't need.

Most, if not all, new drives have partition 1 at 2048. Using the space
before it for an ef02 partition will either give you awkward partition
numbers or require removing partition 1 and starting at 34.
You can reorder the partition numbering fairly trivially using the sort
command in gdisk. There's nothing that requires the partitions to keep
the same numbering if you're using RAID and/or LVM and/or UUIDs.

For example:

% diff -u <(sudo fdisk -l /dev/sda) <(sudo fdisk -l /dev/sdb)|wdiff -d
[--- /proc/self/fd/14-]{+++ /proc/self/fd/15+}  2015-07-01 14:20:30.718540414 -0500
@@ -1,10 +1,10 @@
Disk [-/dev/sda:-] {+/dev/sdb:+} 2.7 TiB, 3000592982016 bytes, 5860533168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: [-something-] {+something else+}

Device     Start        End    Sectors  Size Type
[-/dev/sda1-]
{+/dev/sdb1+}     34       2047       2014 1007K BIOS boot
[-/dev/sda2-]
{+/dev/sdb2+}   2048 5860532223 5860530176  2.7T Linux RAID

[All of the drives in this set look like that.]
Point taken. I missed that feature of gdisk.

However you seem to have conceded the larger point about UEFI which M$ is trying to make mandatory.


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