Subject: bug#22180: Partition alignment using parted (Phillip Susi)

From: "Roderick W. Smith" <[email-masked]>
Date: Sat, 26 Dec 2015 16:44:05 -0500

On 12/26/2015 12:00 PM, [email-masked] wrote:
> 
> On 12/24/2015 05:51 AM, Ankur Tank wrote:
>> Thank you for replying Phillip, 1. How do we measure performance 
>> improvement before and after partition alignment ?
> 
> hdparm -t or dd between the drive and /dev/null or /dev/zero and the
> drive ( for a destructive write test ).

I don't think you'd get much out of that. The alignment issues are
intimately tied to filesystem design features (and kernel
implementations of same). Thus, I'd suggest copying files between the
partitions you want to test and some other device. Several years ago, I
ran some tests, and eventually updated them on newer disks. The end
result of my tests is written up here:

https://www.ibm.com/developerworks/linux/library/l-linux-on-4kb-sector-disks/

One takeaway from this is that the results vary significantly from one
computer and disk to another, as well as from one filesystem to another.
In most cases, improper-alignment penalties are greatest when writing
small files. When reading files or when writing large files, penalties
are much less severe.

-- 
Rod Smith
[email-masked]