I have mentioned in an earlier post that I am an owner of a Utilite ARM computer. One of the issues I experienced with the default setup, is that there is no swap partition. That causes Firefox some memory hungry applications to perform badly.
Check for yourself, if swap is activated on your machine:
$ free
total used free shared buffers cached
Mem: 2006476 263752 1742724 20100 21428 107388
-/+ buffers/cache: 134936 1871540
Swap: 0 0 0
As you can see in the output, no swap space is used. So we are going to see how we can resize a linux ext2/ext3/ext4 partition to make space for a swap partition. We are then going to create a new swap partition and activate it on boot.
Prerequisites
- Prepare a bootable microSD or USB drive. You can use the Utilite Linux Installer for this, or install the official Utilite Linux Image on a removable device.
Checking the current setup
After you boot using a removable medium, you can follow this procedure to check the current setup:
$ sudo fdisk -l /dev/sda
Disk /dev/sda: 29.8 GiB, 32017047552 bytes, 62533296 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
Disklabel type: dos
Disk identifier: 0xa5161f73
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 206847 204800 100M c W95 FAT32 (LBA)
/dev/sda2 206848 62533295 62326448 29.7G 83 Linux
START_SECTOR= 206848END_SECTOR= 62533295TOTAL_SECTORS= 62326448
As you can see, the main root partition (sda2) has a size of 29.7GB. We will reduce it to 28GB and you the rest of the space (1.7GB) for swap. That should be more than enough.
Now in order to avoid tedious calculations, and make sure the filesystem on sda2 takes all available space on the partition we are going to use this trick:
- Resize the sda2 filesystem to 27GB.
- Resize the sda2 partition to 28GB.
- Resize the sda2 filesystem to all available space of the sda2 partition (28GB).
Temporarily resize sda2
- First force check the filesystem for errors:
$ sudo e2fsck -f /dev/sda2If it finishes without errors move to the next step
-
Resize the filesystem to 27GB:
$ sudo resize2fs /dev/sda2 27G - Verify the result:
$ sudo dumpe2fs /dev/sda2 | grep Block | head -2 dumpe2fs 1.42.12 (29-Aug-2014) Block count: 7077888 Block size: 4096 $ echo '(7077888 * 4096)/1024/1024/1024' | bc -l 27.00000000000000000000Exactly 27GB.
Resize the sda2 partition
To resize the sda2 partition we will delete it temporarily and recreate it using the same START_SECTOR but a different END_SECTOR.
- To calculate the new end sector you can use this formula:
NEW_END_SECTOR = START_SECTOR + TOTAL_SECTORS * 28 / 29.7$ echo "206848+62326448*28/29.7" | bc -l 58965788.87542087542087542087We can round up the
NEW_END_SECTORto 58965789.
Use fdisk to resize the partition:
-
Delete the sda2 partition:
$ sudo fdisk /dev/sda Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): d Partition number (1,2, default 2): 2 Partition 2 has been deleted.Verify that sda2 is deleted:
Command (m for help): p Disk /dev/sda: 29,8 GiB, 32017047552 bytes, 62533296 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 Disklabel type: dos Disk identifier: 0xa5161f73 Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 206847 204800 100M c W95 FAT32 (LBA)It is deleted, but not really until you issue the write command.
-
Create a smaller sda2 partition:
Command (m for help): n Partition type p primary (1 primary, 0 extended, 3 free) e extended (container for logical partitions) Select (default p): p Partition number (2-4, default 2): First sector (206848-62533295, default 206848): Last sector, +sectors or +size{K,M,G,T,P} (206848-62533295, default 62533295): 58965789 Created a new partition 2 of type 'Linux' and of size 28 GiB.For the end sector we use the value of the
NEW_END_SECTORwe have calculated earlier. Now let’s verify the new partition:Command (m for help): p Disk /dev/sda: 29,8 GiB, 32017047552 bytes, 62533296 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 Disklabel type: dos Disk identifier: 0xa5161f73 Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 206847 204800 100M c W95 FAT32 (LBA) /dev/sda2 206848 58965789 58758942 28G 83 Linux - Create a new partition of type swap:
Command (m for help): n Partition type p primary (2 primary, 0 extended, 2 free) e extended (container for logical partitions) Select (default p): p Partition number (3,4, default 3): First sector (58965790-62533295, default 58966016): Last sector, +sectors or +size{K,M,G,T,P} (58966016-62533295, default 62533295): Created a new partition 3 of type 'Linux' and of size 1,7 GiB. Command (m for help): t Partition number (1-3, default 3): 3 Partition type (type L to list all types): 82 Changed type of partition 'Linux' to 'Linux swap / Solaris'.Verify that the new partition is created:
Command (m for help): p Disk /dev/sda: 29,8 GiB, 32017047552 bytes, 62533296 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 Disklabel type: dos Disk identifier: 0xa5161f73 Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 206847 204800 100M c W95 FAT32 (LBA) /dev/sda2 206848 58965789 58758942 28G 83 Linux /dev/sda3 58966016 62533295 3567280 1,7G 82 Linux swap / SolarisSeems OK.
-
Write changes and exit:
Command (m for help): w The partition table has been altered. Calling ioctl() to re-read partition table.Remember that nothing is changed unless you issue the write command. If you make a mistake, just hit Ctrl+c and no harm done.
- Resize the filesystem to the full size of the partition:
-
Force check the filesystem
$ sudo e2fsck -f /dev/sda2 - Resize the filesystem to occupy all the available space in the partition:
$ sudo resize2fs /dev/sda2Running
resize2fswithout a size definition, extends the size of the filesystem to the size of the partition. -
Verify the new filesystem size:
$ sudo dumpe2fs /dev/sda2 | grep Block | head -2 dumpe2fs 1.42.13 (17-May-2015) Block count: 7344867 Block size: 4096The size in bytes is
BLOCK_COUNT * BLOCK_SIZEi.e. 7344867 * 4096 = 30084575232. The size in GB is:$ echo '(7344867 * 4096)/1024/1024/1024' | bc -l 28.01844406127929687500
Restart into your internal drive
At this point we need to restart into the Operating System installed on the internal SATA device and check if everything works:
$ sudo fdisk -l /dev/sda
Disk /dev/sda: 29,8 GiB, 32017047552 bytes, 62533296 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
Disklabel type: dos
Disk identifier: 0xa5161f73
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 206847 204800 100M c W95 FAT32 (LBA)
/dev/sda2 206848 58965789 58758942 28G 83 Linux
/dev/sda3 58966016 62533295 3567280 1,7G 82 Linux swap / Solaris
The partition table appears to be correct. But we haven’t formatted the swap partition yet:
$ free
total used free shared buffers cached
Mem: 2006476 264380 1742096 20100 21568 107800
-/+ buffers/cache: 135012 1871464
Swap: 0 0 0
We need to format the swap partition before we can use it.
Setup the swap partition
- Format the swap partition:
$ sudo mkswap /dev/sda3 mkswap: /dev/sda3: warning: wiping old swap signature. Setting up swapspace version 1, size = 1,7 GiB (1826443264 bytes) no label, UUID=fa1e99ff-a9ab-4fd7-ba81-e5020f4e604bTake a note of the UUID: fa1e99ff-a9ab-4fd7-ba81-e5020f4e604b
-
Activate swap:
$ sudo swapon /dev/sda3 - Verify swap (in human readable form this time):
$ free -m total used free shared buffers cached Mem: 1959 259 1700 19 21 105 -/+ buffers/cache: 132 1826 Swap: 1741 0 1741So we have a total of 1741MB of swap space.
-
Setup persistent swap.
To have swap activated persistently across reboots, we need to set it up in /etc/fstab:
# echo 'UUID="fa1e99ff-a9ab-4fd7-ba81-e5020f4e604b" none swap defaults 0 0' >> /etc/fstabYou need to run the above command as root.
Now after you reboot you can check with free to see if the swap space is activated.