Subject: RE: Partition alignment using parted

From: Ankur Tank <[email-masked]>
Date: Tue, 15 Dec 2015 12:32:35 +0000

Hi Experts,

I used following in my script,
I am not sure if below behavior is bug or expected behavior Just to confirm,

parted --script -a optimal /dev/mmcblk0 \

      mklabel gpt \

      mkpart primary    0%              219s \

      mkpart primary    220s    475s \

      mkpart primary    476s    731s \

      mkpart primary    732s    987s \

      mkpart primary    988s    3035s \

      mkpart primary    3036s   5083s \

      mkpart primary    5084s   6107s \

      mkpart primary    6108s   6363s \

      mkpart primary    6364s   16603s \

      mkpart primary    16604s  26843s \

      mkpart primary    26844s  37083s \

      mkpart primary    37084s  37595s \

      mkpart primary    37596s  38107s \

      mkpart primary    38108s  38619s \

      mkpart primary    38620s  73403s \

      mkpart primary    73404s  483003s \

      mkpart primary    483004s 892603s \

      mkpart primary    892604s 1097403s \

      mkpart primary    1097404s        1220283s \

      mkpart primary    1220284s        1629883s \

      mkpart primary    1629884s        1701563s \

      mkpart primary    1701564s        100%

But I see following message from parted,

Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.

When I list partitions I see following values
(---------Last column I added to inform that I expected which size size--------)

# parted --list
Model: MMC MMC04G (sd/mmc)
Disk /dev/mmcblk0: 3842MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system  Name     Flags     Expected Size(in KB)
 1      17.4kB  113kB   95.2kB               primary            110
 2      113kB   244kB   131kB                primary            128
 3      244kB   375kB   131kB                primary            128
 4      375kB   506kB   131kB                primary            128
 5      506kB   1554kB  1049kB               primary            1024
 6      1554kB  2603kB  1049kB               primary            1024
 7      2603kB  3127kB  524kB                primary            512
 8      3127kB  3258kB  131kB                primary            128
 9      3258kB  8501kB  5243kB               primary            5120
10      8501kB  13.7MB  5243kB               primary            5120
11      13.7MB  19.0MB  5243kB               primary            5120
12      19.0MB  19.2MB  262kB                primary            256
13      19.2MB  19.5MB  262kB                primary            256
14      19.5MB  19.8MB  262kB                primary            256
15      19.8MB  37.6MB  17.8MB               primary            17392
16      37.6MB  247MB   210MB                primary            204800
17      247MB   457MB   210MB                primary            204800
18      457MB   562MB   105MB                primary            102400
19      562MB   625MB   62.9MB               primary            61440
20      625MB   835MB   210MB                primary            204800
21      835MB   871MB   36.7MB               primary            35840
22      871MB   3842MB  2971MB               primary            2969600

Could someone explain why parted is not giving partition size which I expected ? Because I had aligned partitions to sector boundaries(sector size 512B).

Any suggestions/pointers/corrections ?

Thank you,

Regards,
Ankur

-----Original Message-----
From: Ankur Tank
Sent: Tuesday, December 15, 2015 3:56 PM
To: [email-masked]'
Cc: [email-masked]
Subject: Partition alignment using parted

Hi Parted Experts,

I am working on am335x based board.
We are using eMMC and as a storage medium and parted for partitioning eMMC.

I am not able to use "optimal" alignment option with parted when partitioning eMMC.
I get following error messages when I use "optimal" alignment

Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.
Warning: The resulting partition is not properly aligned for best performance.

1. Do we have to worry about this message ?

I have put question on Unix & Linux Stackexchange also below is the link for the same http://unix.stackexchange.com/questions/248939/how-to-achieve-optimal-alignment-for-emmc-partition

Now parted reports logical and physical sector size as same.
"Sector size (logical/physical): 512B/512B"

2. Now my question is, is physical size reported by parted is physical sector size or emulated physical sector size?
3.  How can we achieve optimal alignment ? Any suggestions?

Thank you,

Regards,
Ankur

L&T Technology Services Ltd

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