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Fackamato

Member

Registered: 2006-03-31

Posts: 579

[SSD], are my partitions (correctly) aligned?

OCZ Agility 3 (SATA2 limited)

hdparm -I /dev/sdb

/dev/sdb:

ATA device, with non-removable media
    Model Number:       OCZ-AGILITY3                            
    Serial Number:      OCZ-U0S3NZG2420IO1W1
    Firmware Revision:  2.08    
    Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
Standards:
    Used: unknown (minor revision code 0x0110) 
    Supported: 9 8 7 6 5 
    Likely used: 9
Configuration:
    Logical        max    current
    cylinders    16383    16383
    heads        16    16
    sectors/track    63    63
    --
    CHS current addressable sectors:   16514064
    LBA    user addressable sectors:  117231408
    LBA48  user addressable sectors:  117231408
    Logical  Sector size:                   512 bytes
    Physical Sector size:                   512 bytes
    Logical Sector-0 offset:                  0 bytes
    device size with M = 1024*1024:       57241 MBytes
    device size with M = 1000*1000:       60022 MBytes (60 GB)
    cache/buffer size  = unknown
    Nominal Media Rotation Rate: Solid State Device

fdisk -l:

$ sudo fdisk -l /dev/sdb

Disk /dev/sdb: 60.0 GB, 60022480896 bytes
255 heads, 63 sectors/track, 7297 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00025741

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          32      248832   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sdb2              32        7298    58363905    5  Extended
/dev/sdb5              32        7298    58363904   83  Linux

sectors:

Command (m for help): p

Disk /dev/sdb: 60.0 GB, 60022480896 bytes
255 heads, 63 sectors/track, 7297 cylinders, total 117231408 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00025741

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048      499711      248832   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sdb2          501758   117229567    58363905    5  Extended
/dev/sdb5          501760   117229567    58363904   83  Linux

sdb1 is /boot
sdb2 is the extended partition in which the logical partition sdb5 resides. sdb5 has a LUKS container (setup with default parameters), then a LVM physical volume is created (default params)  in that (takes all the space).
On the PV we have a VG that takes all space, and in that VG I have a 20GB root, 512MB swap and the rest for home ( ~35.16GB).

I guess I've a few questions, first, are the partitions aligned on the SSD? Secondly, when you create a LUKS container, do you need to do something special in order to have it aligned?

Many thanks!

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: [SSD], are my partitions (correctly) aligned?

Did you check out the wiki entry on SSDs?  It recommends using GPT, but also explains how to ensure proper alignment with MBR.

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Fackamato

Member

Registered: 2006-03-31

Posts: 579

Re: [SSD], are my partitions (correctly) aligned?

Did you check out the wiki entry on SSDs?  It recommends using GPT, but also explains how to ensure proper alignment with MBR.

I'm checking it out now. This is actually a Lubuntu install, so it did all the partitioning etc itself. I'm beginning to suspect that I have to redo everything manually!

edit:

Disk /dev/sdb: 60.0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system  Flags
1      1049kB  256MB   255MB   primary   ext2         boot
2      257MB   60.0GB  59.8GB  extended
5      257MB   60.0GB  59.8GB  logical

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): u
Changing display/entry units to sectors

Command (m for help): p

Disk /dev/sdb: 60.0 GB, 60022480896 bytes
32 heads, 32 sectors/track, 114483 cylinders, total 117231408 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00025741

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048      499711      248832   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sdb2          501758   117229567    58363905    5  Extended
Partition 2 does not end on cylinder boundary.
/dev/sdb5          501760   117229567    58363904   83  Linux

Hm, looks like the first partition is at least aligned in the beginning, but I'm not sure about the end, or sdb2 or sdb5.

Last edited by Fackamato (2011-08-03 16:24:49)

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,697

Website

Re: [SSD], are my partitions (correctly) aligned?

Dunno... I would highly recommend using GTP; gdisk takes care of this important step.

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Viper_Scull

Member

From: London, UK

Registered: 2011-01-15

Posts: 153

Re: [SSD], are my partitions (correctly) aligned?

AFAIK, Ubuntu aligns correctly only if you create just 1 partition. If you create more than one you need to do it with fdisk (or gdisk if you use GPT).

I aligned my Vertex 2 with fdisk cause i was using MBR since at that time i was dual-booting with W7. This is how it looks

bary ~ $ fdisk -l /dev/sda

Disk /dev/sda: 60.0 GB, 60022480896 bytes
32 heads, 32 sectors/track, 114483 cylinders, total 117231408 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x756ac31b

   Device Boot      Start         End      Blocks   Id  System
/dev/sda2   *    64453632    95704063    15625216   83  Linux
/dev/sda3        95704064   117230591    10763264   83  Linux

There is no-partitioned space at the beginning cause i erased W7 but the important thing if you're using fdisk is that the first partition starts at the second cylinder . thus, all subsequent partitions will be aligned.

I'd recommend you in case you didnt do it to align your filesystems as well.

Last edited by Viper_Scull (2011-08-04 00:23:14)

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