Re: Calculating optimal disk partitions
On Tuesday, May 7, 2013 19:50, "Bob Proulx" <bob@proulx.com> said:
> craig@gtek.biz wrote:
>> craig@gtek.biz said:
>> I found a thread that mentioned the values should be multiples of
>> 2048 for advanced format disks, which this ST31000524AS is, if I'm
>
> The ST31000524AS is not advanced format. It uses traditional 512 byte
> sectors. I have several of that particular model of drive.
>
>> reading the product specs correctly. But both
>> /sys/block/sdb/queue/physical_block_size and
>> /sys/block/sdb/queue/logical_block_size report 512, which is why I
>> asked about how to determine the actual sector size.
>
> The actual sector size is 512.
>
> # hdparm -I /dev/sda
> ...
> Logical/Physical Sector size: 512 bytes
Thanks Bob. You have at least confirmed one thing for me. Interestingly, the documentation that is linked to the hard drive on the Seagate site that mentions the disk as being advanced format is not the documentation for this drive, and I missed that. I had forgotten about hdparm as well.
> ...
>
> If it is advanced format then it would have reported it like this:
>
> Logical Sector size: 512 bytes
> Physical Sector size: 4096 bytes
>
> Example using the new partitioner in the new debian-installer. This
> would be good everywhere.
>
> # sfdisk -d /dev/sda
> # partition table of /dev/sda
> unit: sectors
>
> /dev/sda1 : start= 2048, size= 997376, Id=fd
> ...
>
> Example using the old partitioner in the old debian-installer. This
> is fine for 512 byte sectors but not for 4k sector disks.
>
> # sfdisk -d /dev/sda
> # partition table of /dev/sda
> unit: sectors
>
> /dev/sda1 : start= 63, size= 995967, Id=fd
> ...
>
> I am sorry but I do not have a good explanation of the rest of your
> question. I just responded about the part I knew.
No need to apologize, I appreciate you sharing what you could. I will go play with sfdisk and see if that sheds any light on the subject. I just find it frustrating that the partitioner would issue a warning that has so little supporting documentation. Reminds me of another operating system that I had the misfortune of certifying on many years ago. FWIW, I did find an interesting article by a Roderick Smith (http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/) that talks about advanced format disks, but still doesn't explain the process for calculating optimal start and end points for creating partitions. I will check out the rest of his articles and keep looking as well. Maybe my search skills need some honing, eh?
Craig
>
> Bob
>
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