RE: Calculating optimal disk partitions
On Monday, May 6, 2013 08:39, craig@gtek.biz said:
> This 1TB disk reports both physical and logical sector sizes of 512 bytes each,
> and is currently partitioned with one extended partition that is made up of the
> entire disk. It has three existing logical partitions, and parted tells me the
> first two are aligned, and the third is not. I would like to leave the existing
> partitions as they are, and create one more optimally aligned partition. The
> existing layout is as follows, and an example of what I did in trying to create a
> 100GB partition:
>
> $ sudo parted -a opt /dev/sdb
> GNU Parted 2.3
> Using /dev/sdb
> Welcome to GNU Parted! Type 'help' to view a list of commands.
> (parted) unit s
> (parted) p
> Model: ATA ST31000524AS (scsi)
> Disk /dev/sdb: 1953525168s
> Sector size (logical/physical): 512B/512B
> Partition Table: msdos
>
> Number Start End Size Type File system Flags
> 1 2048s 1953523711s 1953521664s extended lba
> 5 4096s 683732991s 683728896s logical
> 6 683735040s 976762879s 293027840s logical
> 7 976762943s 1172081149s 195318207s logical
>
> (parted) mkpart
> Partition type? primary/logical? logical
> File system type? [ext2]?
> Start? 1172083200
> End? 1953523703
> Warning: The resulting partition is not properly aligned for best performance.
> Ignore/Cancel? c
> (parted) q
>
>
> Can anyone tell me what values I should use for the starting and ending sectors
> for the next partition so that I do not get the error message? Would anyone be
> willing to share the mathematical calculation that helps determine those values (I
> am assuming there is one since parted is able to make assertions based on
> something)? Is it possible that the physical sector size is 4096 bytes, and if so
> how would I determine that, and how does that affect things?
I found a thread that mentioned the values should be multiples of 2048 for advanced format disks, which this ST31000524AS is, if I'm 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.
However, that advice seems to have worked in this instance. If it's not too much trouble, can anyone shed more light on the subject? Do I need to align on multiples of 2048 sectors, or just 8? And yes, I know that 2048 is a multiple of 8.
(parted) mkpart
Partition type? primary/logical? l
File system type? [ext2]?
Start? 1172082688
End? 100%
(parted) p
Model: ATA ST31000524AS (scsi)
Disk /dev/sdb: 1953525168s
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 2048s 1953523711s 1953521664s extended lba
5 4096s 683732991s 683728896s logical
6 683735040s 976762879s 293027840s logical
7 976762943s 1172081149s 195318207s logical
8 1172082688s 1953523711s 781441024s logical
(parted) q
> FWIW, at this point I don't care about the fact that partition 7 is not properly
> aligned, and I don't care if I have to leave some space unused. I just want to
> understand how to avoid the error while using as much of the available space as I
> can in an optimal manner.
>
> Any light is appreciated.
>
> Craig
>
>
> Sent - Gtek Web Mail
>
>
>
> --
> To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org
> with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
> Archive: [🔎] 1367847550.77611068@webmail.gtek.biz">http://lists.debian.org/[🔎] 1367847550.77611068@webmail.gtek.biz
>
>
Sent - Gtek Web Mail
Reply to: