Parted: Solving Partitioning Problems on Large Filesystems
| Software version | 2.1 |
| Operating System | Debian 6 Red Hat 6.3 |
| Last Update | 13/02/2013 |
Introduction
GNU Parted is a program for creating, destroying, resizing, checking, and copying partitions, and the file systems on them. This is useful for creating space for new operating systems, reorganizing hard disk usage, copying data between hard disks, and disk imaging. It was written by Andrew Clausen and Lennert Buytenhek.
It consists of a library, libparted, and a command-line frontend, parted, that also serves as reference implementation.
Currently, Parted runs only under Linux, GNU/Hurd, FreeBSD and BeOS.
Problem Statement
You may have just acquired a disk array (SATA, SAS…) and are encountering partitioning issues. For example, you might not be able to create partitions larger than 99GB or 2TB. This is what happened to me. And in your boot logs (dmesg), you might see errors like:
sdb : very big device. try to use READ CAPACITY(16).
Losing some ticks... checking if CPU frequency changed.
SCSI device sdb: 8784445440 512-byte hdwr sectors (4497636 MB)
sdb: Write Protect is off
sdb: Mode Sense: 1f 00 10 08
SCSI device sdb: drive cache: write through w/ FUA
sdb: sdb1
sdb : very big device. try to use READ CAPACITY(16).
SCSI device sdb: 8784445440 512-byte hdwr sectors (4497636 MB)
sdb: Write Protect is off
sdb: Mode Sense: 1f 00 10 08
SCSI device sdb: drive cache: write through w/ FUA
sdb:
sdb : very big device. try to use READ CAPACITY(16).
SCSI device sdb: 8784445440 512-byte hdwr sectors (4497636 MB)
sdb: Write Protect is off
sdb: Mode Sense: 1f 00 10 08
SCSI device sdb: drive cache: write through w/ FU
You likely partitioned with fdisk or cfdisk. And that’s where your error lies! Apparently, these tools still have difficulty handling large capacities. That’s why I’m recommending parted :-)
Installation
Quite simple:
apt-get install parted
Partitioning
Wizard
My partitioning is fairly simple; I want to create a single 4.5TB disk. First, I check that I don’t have any existing partitions and I begin:
$ parted
GNU Parted 1.7.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Disk /dev/sda: 145GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 32,3kB 41,1MB 41,1MB primary fat16
2 41,1MB 173MB 132MB primary ext3 boot
3 173MB 145GB 145GB primary lvm
Here we can see that I’m on my first disk (sda) and not on my array (sdb). Let’s switch to it:
(parted) select /dev/sdb
Using /dev/sdb
Let’s create a label:
(parted) mklabel
New disk label type? [msdos]? gpt
Next, create the partition:
(parted) mkpart
Partition name? []? san # Give any name you want
File system type? [ext2]? ext3 # The filesystem
Start? 0 # The beginning of your disk
End? -1 # -1 corresponds to the end
For those who want to use LVM, simply add a flag:
set 1 lvm on
Command line
If you want to do everything from the command line, for example to automate the process, here’s how. I’ve made a small script that creates a partition taking up the entire disk and optimizes it (via disk alignment) for the best performance:
datas_device=/dev/sdb
parted -s -a optimal $datas_device mklabel gpt
parted -s -a optimal $datas_device mkpart primary ext4 0% 100%
parted -s $datas_device set 1 lvm on
- Line 1: we create a gpt-type label for large partitions (greater than 2TB)
- Line 2: we create a partition that takes up the entire disk
- Line 3: we indicate that this partition will be LVM type
Validation
We can see the result:
(parted) p
Disk /dev/sdb: 4498GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 17,4kB 4498GB 4498GB ext3 san
Everything looks good. I can exit:
(parted) q
And verify once more:
$ cat /proc/partitions
major minor #blocks name
8 0 142082048 sda
8 1 40131 sda1
8 2 128520 sda2
8 3 141910177 sda3
8 16 4392222720 sdb
8 17 4392222686 sdb1
254 0 2097152 dm-0
254 1 20971520 dm-1
254 2 20971520 dm-2
254 3 20971520 dm-3
254 4 76894208 dm-4
Formatting
All that’s left is to format it in the desired format (ext3 in this case):
mkfs.ext3 /dev/sdb1
Maximum Filesystem Sizes
| Filesystem | Maximum partition size | Maximum file size |
|---|---|---|
| ext2 | 8 TB | 2 GB |
| ext3 | 8 TB | 2 TB |
| ext4 | 1024 PB | |
| Resiser4 | 8 TB | |
| ZFS | 16 EB | 16 EB |
Last updated 13 Feb 2013, 12:54 +0200.