Questions about default partitioning scheme.

Rademes · 2016-03-23 14:49

Good day!
When I installed Q4OS from Live CD, I have chosen the default partitioning scheme.
Now when I checked it using fdisk, I have noticed message Partition 2 does not start on physical sector boundary.

Is it everything OK with partitioning?

Also, for what purpose these unallocated spaces are made before first and third partition? I haven`t seen in partitioning manuals, that they should be made.

Dai_trying · 2016-03-23 15:06

I believe this is to do with partitioning being aligned to mb's rather than cylinders, it has happened on various systems I have used and i have had no ill effect on usability. Although I don't know if the free space has any purpose.

q4osteam · 2016-03-23 15:09

Rademes wrote:

I have chosen the default partitioning scheme

What does the 'default scheme' mean exactly, which way did you choose it ?

Rademes · 2016-03-23 19:04

Actually, I am not exactly chosen it (written a bit wrong, sorry).
I booted from LiveCD, then clicked on Install Q4OS, then followed setup screens, then I accepted partitioning scheme which was offered by Q4OS installer. I haven`t changed anything in partitioning screen, just accepted the default scheme which was offered by Q4OS installer.
One thing, before booting from LiveCD I wiped first two gigabytes of my HDD using sudo dd if=/dev/zero ... command.

Last edited by Rademes (2016-03-23 19:05)

q4osteam · 2016-03-23 20:45

Rademes wrote:

I accepted partitioning scheme which was offered by Q4OS installer

The installer doesn't partition harddrive, it only shows current existing partitions on that drive. User can assign types of partitions and choose how to format them, for ex. '/', 'swap', 'home', etc...

Rademes wrote:

I have noticed message Partition 2 does not start on physical sector boundary.

The partitioning you mention has existed before you ran the installer, including wrong boundary alignment. It wasn't offered by installer as an appropriate schema, but already existing partitions has been displayed.

If you want to make your own partitioning schema, you have to click 'Edit partitions' button during installation and create desired partitions manually. Alternatively you can re-partition the drive using GParted or another partitioning tool before you start installer.

Rademes · 2016-03-23 22:12

q4osteam wrote:

The installer doesn't partition harddrive, it only shows current existing partitions on that drive.

Well, that is very strange, because I wiped first 2 gigabytes of my HDD using "sudo dd if=/dev/zero" command before running install, so old partition table should be wiped too...

q4osteam · 2016-03-24 00:18

Rademes wrote:

... because I wiped first 2 gigabytes of my HDD using "sudo dd if=/dev/zero" command before running install...

Oh sure, you wiped drive's partitions before, we have overlooked that, sorry. In that case the installer rises a 'No partition table was found ... Yes / No' dialog and prompt you to create default/automatic partitioning scheme, you're right. This partitioning tool, as well as complete installer, is derived from Mint LMDE live-cd installer, we haven't exactly analyzed the partitioning routine. We have tested it on couple of drives and there were no physical sector overflow, all tables were aligned. It probably depends on particular harddrive type /size. Also, there shouldn't be a reason to create unallocated space, however it doesn't bother.

Rademes · 2016-03-24 06:59

So, is it possible to align partitions by moving them using GParted without necessity to reinstall entire OS?

Last edited by Rademes (2016-03-24 08:18)

q4osteam · 2016-03-24 09:28

In addition, the Mint LMDE partitioning method aligns tables to 1MiB not physical cylinder, it results in 1MB gaps between some partitions. It's common effect on various systems, as Dai_trying wrote above.

Unfortunately we are not sure, if parted/GParted is capable to safely re-align partitions from MiBs to Cylinders. You would have to try it out on your own. You can get some valuable info from 'man parted' manual page.

bin · 2016-03-24 13:20

http://gparted.sourceforge.net/display- … -alignment

Use MiB alignment for modern operating systems. This setting aligns partitions to start and end on precise mebibyte (1,048,576 byte) boundaries. MiB alignment provides enhanced performance when used with RAID systems and with Solid State Drives, such as USB flash drives.

The Cylinder/Head/Sector values reported by modern disk devices no longer have a direct physical relationship to the data stored on the disk device. Hence it is no longer valid to use this alignment (Cylinders) setting to achieve enhanced performance.

1. Boot Live Media
2. Run Gparted
3. Get rid of all partitions - clear drive completely
4. Create new msdos filesystem
5. Create 30Gb partition ext4 - you'll use this for /
6. Create 4gb partition - SWAP
7. Create 99xxxGb ext4 partition with whatever is left for /home

If you wish, instead, you can create an extended partition with remainder of drive after 5 - this will become sda2.
Then in that extended partition create logical drives for SWAP and /home which will be sda5 and sda6 respectively

All should be aligned on Mib as per Gparted team instructions

There will be a few spare mb floating around - this is normal.

Dai_trying · 2016-03-24 13:26

Or alternatively you could just ignore a 1Mb loss of hdd, does that 1Mb really warrant all the effort to regain it? I usually just leave them, but that is my personal preference.

Rademes · 2016-03-24 15:34

Dai_trying wrote:

Or alternatively you could just ignore a 1Mb loss of hdd, does that 1Mb really warrant all the effort to regain it?

No, it does not bother me.

q4osteam wrote:

Unfortunately we are not sure, if parted/GParted is capable to safely re-align partitions from MiBs to Cylinders. You would have to try it out on your own.

I decided to leave it as it is, because I haven`t noticed any performance degradation. Hope, it will not shorten life of my HDD.
Thank you for help.
Next time I will perform partitioning manually using GParted before installation. I will follow bin`s advice.
https://www.thomas-krenn.com/en/wiki/Pa … _Alignment

Last edited by Rademes (2016-03-24 19:02)

Rademes · 2016-04-09 07:30

Problem was solved by moving first partition using GParted and choosing default option "Align to - MiB". Now all partitios are aligned! No OS reinstall was needed.
http://storage6.static.itmages.ru/i/16/ … a9afa5.png
http://storage7.static.itmages.ru/i/16/ … 06d3bf.png

Q4OS Forum

#1 2016-03-23 14:49

Questions about default partitioning scheme.

#2 2016-03-23 15:06

Re: Questions about default partitioning scheme.

#3 2016-03-23 15:09

Re: Questions about default partitioning scheme.

#4 2016-03-23 19:04

Re: Questions about default partitioning scheme.

#5 2016-03-23 20:45

Re: Questions about default partitioning scheme.

#6 2016-03-23 22:12

Re: Questions about default partitioning scheme.

#7 2016-03-24 00:18

Re: Questions about default partitioning scheme.

#8 2016-03-24 06:59

Re: Questions about default partitioning scheme.

#9 2016-03-24 09:28

Re: Questions about default partitioning scheme.

#10 2016-03-24 13:20

Re: Questions about default partitioning scheme.

#11 2016-03-24 13:26

Re: Questions about default partitioning scheme.

#12 2016-03-24 15:34

Re: Questions about default partitioning scheme.

#13 2016-04-09 07:30

Re: Questions about default partitioning scheme.

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