GDISK say "align partitions on 4096 boundaries" but does not

[bozo29]

Subject: NWSP2 lite + WD Green 3TB HDD (WD30EZRX).

I did GPT partitions with GParted, then I wanted to align with GDISK.
GDISK say "align partitions on 4096 boundaries" but does not.

Here's the result:

Code: Select all

root@partedmagic:~# gdisk /dev/sdc
GPT fdisk (gdisk) version 0.8.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): p
Disk /dev/sdc: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 0BB3EDA1-1EAE-47BE-862A-C35B97D07BD6
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 2925 sectors (1.4 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         1050623   512.0 MiB   0700 
   2         1050624         2099199   512.0 MiB   0700 
   3         2099200         3147775   512.0 MiB   8200 
   4         3147776         3164159   8.0 MiB     0700 
   5         3164160         4771839   785.0 MiB   0700 
   6         4771840         4788223   8.0 MiB     0700 
   7         4788224         5836799   512.0 MiB   0700 
   8         5836800      5860532223   2.7 TiB     0700 

Command (? for help): x

Expert command (? for help): l
Enter the sector alignment value (1-65536, default = 2048): 4096             

Expert command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): Y
OK; writing new GUID partition table (GPT) to /dev/sdc.
The operation has completed successfully.
root@partedmagic:~# gdisk /dev/sdc
GPT fdisk (gdisk) version 0.8.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): p
Disk /dev/sdc: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 0BB3EDA1-1EAE-47BE-862A-C35B97D07BD6
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 2925 sectors (1.4 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         1050623   512.0 MiB   0700 
   2         1050624         2099199   512.0 MiB   0700 
   3         2099200         3147775   512.0 MiB   8200 
   4         3147776         3164159   8.0 MiB     0700 
   5         3164160         4771839   785.0 MiB   0700 
   6         4771840         4788223   8.0 MiB     0700 
   7         4788224         5836799   512.0 MiB   0700 
   8         5836800      5860532223   2.7 TiB     0700 

Command (? for help):

Where is the problem?

However, my nwsp2-lite works fine without this alignment.
So I have a question:
It is imperative that this alignment be done?
In what way can affect the proper functioning of the hard disk, if I do not.

What I mean is that I prefer to try to do so now, if absolutely need it, than to take it from the start with partitioning, after I got to put 1 or 2TB of files onHDD.

Any advice?

Thanks in advance

[Jocko]

Hi Bozo29,

The last week, I format a gpt disk. You made an error in the expert menu.

After selecting the sector alignment value (option l) you must go back to the main menu (option m) and not do a write command (option w).

And when you are in the main menu, gdisk uses the new value (4096) when you will create the partition.

gdisk-align-value.jpg

Note for a 3TB disk the gpt table is :

Code: Select all

Disk /dev/sda: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00000000-0000-0000-0000-000000000000
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 4096-sector boundaries
Total free space is 4062 sectors (2.0 MiB)
Number  Start (sector)    End (sector)  Size       Code  Name
   1            4096         1052671   512.0 MiB   8300  Linux filesystem
   2         1052672         2101247   512.0 MiB   8300  Linux filesystem
   3         2101248         3149823   512.0 MiB   8200  Linux swap
   4         3149824         3166207   8.0 MiB     8300  Linux filesystem
   5         3166208         4739071   768.0 MiB   8300  Linux filesystem
   6         4739072         4755455   8.0 MiB     8300  Linux filesystem
   7         4755456         5804031   512.0 MiB   8300  Linux filesystem
   8         5804032      5860533134   2.7 TiB     8300  Linux filesystem

[bozo29]

Thank you very, very much for your answer so quickly.

So, I understand that I can't create partitions with gparted and then align them with gdisk.
I have to make partitions with gdisk and do alignment before creating the first partition.
Right?

However, you know if I will be affected in the future, if I leave the hard drive as it is now?
Because it seems to work o.k.

[fvdw]

After having a closer look I think using aligning on 2048 sectors will be ok as well.
As I read it it is then aligned on boundaries of 2048 (logical) sectors. Each (logical) sector =512 Bytes
The issue with advanced format disk is that partition should be aligned on boundary of physical sector size, this is on an advanced format disk 4096 Bytes.
But 2048 sectors of 512 bytes are equal to 256 sectors of 4096 bytes.
This means to my opinion that your disk is aligned on physical sector boundaries and should not suffer from performance degradation

[Jocko]

@fvdw
I think so

[bozo29]

Thank you, fvdw very much for your answer,

But take a look at "SMART INFORMATION SECTION" in fvdw firmware ver. 14.

smartctl 6.0 2012-10-10 r3643 [armv5tel-linux-2.6.39.4] (local build)
Copyright (C) 2002-12, Bruce Allen, Christian Franke, http://www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family: Western Digital Caviar Green (AF)
Device Model: WDC WD30EZRX-00DC0B0
Serial Number: WD-WMC1T1003262
LU WWN Device Id: 5 0014ee 058ca33a8
Firmware Version: 80.00A80
User Capacity: 3,000,592,982,016 bytes [3.00 TB]

Sector Sizes: 512 bytes logical, 4096 bytes physical

Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-2 (minor revision not indicated)
SATA Version is: SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is: Sun Feb 24 13:35:02 2013 GMT+2
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

It is O.K?

Because I'm not lazy to remove the HDD and rebuild partitions.

Any advice is welcome.

[fvdw]

yes to my knowledge it should be ok.

PS you can test just transfer a big video file if it reaches values above 20 MB/s it is for sure ok

[bozo29]

With FileZilla:

Download from nas to laptop, speed is about 30-32MB/s
Upload from laptop to nas, speed is about 20-21MB/s

Seems to be o.k.

Thank you, for your answer