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Re: GPT and SSDs



On 19/05/14 01:50 AM, Reco wrote:
Hi.

On Mon, May 19, 2014 at 12:48:00AM -0400, Gary Dale wrote:
This led me into partitioning. I thought that GPT pretty much gave
you proper partition alignment, but now I think I was mistaken on
that point. gdisk shows my first partition starting at 34, with the
fdisk info showing 255 heads, 63 sectors/track. That doesn't come
close to 4k alignment.
EFI label requires 34*512 disk sectors, so first partition starting on
34 sector is not unusual.


Anyway, my gdisk data is:
   Disk /dev/sda: 234441648 sectors, 111.8 GiB
   Logical sector size: 512 bytes
This. Note that your disk's logical sector is 512 bytes.


Before I haul out sysrescuecd and move my partitions around, I
thought I'd ask for suggestions. Should I move the filesystem to
something that is a multiple of 8, do something else, or look
elsewhere for a solution to my problem?
Aligning disk against 4096 sector would be needed if your disk had 4096
physical sector (or 4096 logical one). This does not seem to be the
case, although you can check disk sector sizes with:

cat /sys/block/sda/queue/logical_block_size

cat /sys/block/sda/queue/physical_block_size

If both of those return 512 - you have nothing to worry about.
If either of them returns 4096 - you'll need to align your partitions.

Reco
both cats report 512.


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