2009.02.08 - bluebear: Uhm... okay, my NSLU2 needs 5 minutes, don't know why. Fortunately (re)booting is not an operation performed very often by me.

20080515 - BenMcDui - It took my system 2min.

2008.04.19 - bluebear: Is it normal that after doing the .ext3flash trick the booting takes a small eternity?

2008.04.19: Is it normal that after doing the .ext3flash trick the booting takes a small eternity?

I've got the firefly mediaserver and bash running alongside the original Linksys app and appr. 5% of 32Mb left...., so it seems. However, the 4900 Kb allocated to the buffers is available for programs directly. Linux is just using this for buffering data for the disks. The 1736 kB which is free, is in effect wasted; it's not used for any purpose.

I've applied the spindown script, which copy all files from /dev and /var into a Ram-filesystem,taken from: http://www.nslu2-linux.org/wiki/FAQ/SpinDownUSBHarddisks. It is a bit dangerous, as the RAM-fs eats up more of the tot available 32Mb, while Ext3flash already has disabled swap.... After a year of using this script, I haven't had problems with this configuration. I can happily use the firefly mediaserver, nfs and the transmission torrent-client, and have no crashes.

I've got the firefly mediaserver and bash running alongside the original Linksys app and appr. 5% of 32Mb left...., so it seems. However, the 4900 Kb allocated to the buffers is available for programs directly. Linux is just using this for buffering data for the disks. The 1736 kB which is free, is in effect wasted; it's not used for any purpose.

Nothing is ever free - and these changes also carry a potential cost. Certain applications may use the "last-accessed" timestamp, and these may misbehave when the accessed-time stamp is disabled (e.g. dropbear started via inetd). Swap space is used when the operating system runs low on main memory. And since the NSLU2 has only a small amount of RAM to begin with, large applications or many applications at the same time may run the system out of memory.

I can happily use the firefly mediaserver, bash, samba and the libbt-library with the torrent-scripts, and have no crashes. Using Amulehowever is impossible; it crashes because of lack of memory after a few minutes. As I read more about Amule-crashes in forums and that people have observed that at least appr. 30 Mb is needed for the administration that emule-clients have to keep, I'm inclined to think that only applying Ext3flash is already enough to let Amule crash, as Ext3flash reduces SWAP-memory to zero.

Reducing the number of writing even more

Note after a few weeks of applying this script: I can happily use the firefly mediaserver, bash, samba and the libbt-library with the torrent-scripts, and have no crashes. Using Amulehowever is impossible; it crashes because of lack of memory after a few minutes. As I read more of these Amule-crashes in forums, I'm inclined to think that only applying Ext3flash is already enough to let Amule crash, as Ext3flash reduces SWAP-memory to zero.

I've got the firefly mediaserver and bash running alongside the original Linksys app and appr. 5% of 32Mb left...., so it seems. However, the 4900 Kb allocated to the buffers is available for programs directly. Linux is just using this for buffering data for the disks. The 1736 kB which is free, is in effect wasted; it's not used for any purpose.

The result on my Unslung6.8 slug with Ext3flash also applied:

I've applied the spindown script, which copy all files from /dev and /var into a Ram-filesystem,taken from: http://www.nslu2-linux.org/wiki/FAQ/SpinDownUSBHarddisks. It is a bit dangerous, as the RAM-fs eats up more of the tot available 32Mb, while Ext3flash already has disabled swap....

The result on my Unslung6.8 slug with Ext3flash also applied (32 Mb RAM is almost used now):

I've got the firefly mediaserver and bash running alongside the original Linksys app and appr. 5% of 32Mb left.... When I play music on my Roku, streaming form the firefly, the amount of free RAM sinks to appr. 800. However, all seems stable. I 'll remove this try-out if it renders unstable.

 #!/bin/sh
 # /etc/init.d/mount_var_dev.sh
 # Script section to create ramdisk for /var and for /dev

 # disable the oom-killer to use the full swap
 /sbin/sysctl -w vm.overcommit_memory=1
 # From JNC : this command does not exist on my slug (release 2.7)

 # better only use /var/log then the full /var
 # following lines might need to be adjusted according to your OS and/or installed services
 /bin/echo "Creating ramfs for /var/log:"
 /bin/mount -t ramfs ramfs /mnt -o maxsize=256
 /bin/cp -rp /var/log/* /mnt/
 /bin/mount -o bind /var/log /var/log.state
 /bin/mount -o bind /mnt /var/log
 /bin/umount /mnt

 /bin/echo "Creating ramfs for /dev:"
 /bin/mount -t ramfs ramfs /mnt -o maxsize=256
 cd /dev
 find . -print0 -mount | cpio -p -0 -d -m -u /mnt
 # you can not use cp command for /dev
 /bin/mount -o bind /dev /dev.state
 /bin/mount -o bind /mnt /dev
 /bin/umount /mnt

 # Uncomment the following line when using debianslug
 #mount devpts /dev/pts -t devpts

 # Return and continue execution of system rc.
 return 1
 # [EOF]

 bash-3.2# free

@@/.

@@/

@@

Note: Unslung 5.5 only supports a flash disk as the root drive on USB Port 1. Unslung 6.x supports the use of a flash disk as the root drive on either USB port, although USB Port 2 is often preferred.

Try-out, reducing the number of writing even more

I've applied the spindown script, which copy all files from /dev and /var into a Ram-filesystem,taken from: http://www.nslu2-linux.org/wiki/FAQ/SpinDownUSBHarddisks. It is a bit dangerous, as the RAM-fs eats up more of the tot available 32Mb, while Ext3flash already has disabled swap..

1. !/bin/sh
2. /etc/init.d/mount_var_dev.sh
3. Script section to create ramdisk for /var and for /dev
4. disable the oom-killer to use the full swap

/sbin/sysctl -w vm.overcommit_memory=1

1. From JNC : this command does not exist on my slug (release 2.7)
2. better only use /var/log then the full /var
3. following lines might need to be adjusted according to your OS and/or installed services

/bin/echo "Creating ramfs for /var/log:" /bin/mount -t ramfs ramfs /mnt -o maxsize=256 /bin/cp -rp /var/log/* /mnt/ /bin/mount -o bind /var/log /var/log.state /bin/mount -o bind /mnt /var/log /bin/umount /mnt

/bin/echo "Creating ramfs for /dev:" /bin/mount -t ramfs ramfs /mnt -o maxsize=256 cd /dev find . -print0 -mount | cpio -p -0 -d -m -u /mnt

1. you can not use cp command for /dev

/bin/mount -o bind /dev /dev.state /bin/mount -o bind /mnt /dev /bin/umount /mnt

1. Uncomment the following line when using debianslug
2. mount devpts /dev/pts -t devpts
3. Return and continue execution of system rc.

return 1

1. [EOF]

The result on my Unslung6.8 slug with Ext3flash also apllied (32 Mb RAM is almost used now):

bash-3.2# free

              total         used         free       shared      buffers
  Mem:        30524        28788         1736            0         4900
 Swap:            0            0            0

I've got the firefly mediaserver and bash running alongside the original Linksys app and appr. 5% left.... When I play music on my Roku, streaming form the firefly, the amount of free RAM sinks to appr. 800. However, all seems stable. I 'll remove this note if it renders unstable.

Special Handling of a Flash Drive for the Unslung Root Drive

Using a flash drive is often an attractive way to run an Unslung NSLU2. It's quiet, small, low-power, and low-cost.

However, they do have a significant disadvantage compared to the traditional hard-drive -- they wear out much, much faster.

A couple of simple changes to how Unslung uses the flash drive can greatly extend the life of the flash device:

• Disabling swapping on the device.
• Disabling the recording of the timestamp each time a file is accessed.

All that is required to instruct Unslung to make the necessary changes is to create a file named /.ext3flash after the system has been successfully unslung and rebooted. The following command will do the trick nicely:

 touch /.ext3flash

Once created, the changes will take effect at the next boot.

Potential Pitfalls

Nothing is ever free - and these changes also carry a potential cost. Certain applications may use the "last-accessed" timestamp, and these may misbehave when the accessed-time stamp is disabled. Swap space is used when the operating system runs low on main memory. And since the NSLU2 has only a small amount of RAM to begin with, large applications or many applications at the same time may run the system out of memory.

Technical Details

During the boot process, if the /.ext3flash file exists, the boot scripts will:

• remount the root partition with -o noatime
• remount the conf partition with -o noatime,sync
• execute swapoff to turn off swapping on the root drive

Note: Unslung 5.5 only supports a flash disk as the root drive on USB Port 1. Unslung 6.x supports the use of a flash disk as the root drive on either USB port, although USB Port 2 is often preferred.

• To make this work on your system simply type: touch /.ext3flash and then reboot your system

1. run swapoff /dev/sda to turn off swapping on a root flash drive.

(These only happen if /.ext3flash is present at boot time)

1. Note: Log files stored in /var will not be saved over shutdowns and reboots. This includes the miau logs which are now stored in /var/spool. If you need to keep log files over reboots and shutdowns consider adding a copy script to rc.reboot and/or rc.halt (note that doing this hasn't been tested yet - we're not sure if the slug runs rc.reboot or rc.halt on every different way that it shuts down or reboots).

• To make this work on your system simply type: touch /share/hdd/conf/.ext3flash and then reboot your system

1. run swapoff /dev/sda to turn off swaping on a root flash drive.

Implemented Changes in Unslung 2.13:

(These only happen if /.ext3flash is present)

1. Move all of /var and /dev to ramfs (This should use around 20KB of memory depending on the size of your logs)

1. Note: Log files stored in /var will not be saved over shutdowns and reboots. This includes the miau logs which are now stored in /var/spool. If you need to keep log files over reboots and shutdowns consider adding a copy script to rc.reboot.

• To make this work on your system simply type: touch /.ext3flash and then reboot your system
• Please report all issues and suggestions to the bug tracker.
• These changes affect both the standard and able variants of the firmware.

1. run swapoff /dev/sda to turn off swaping on a root flash drive (People can modify this if they want swapoff -a)?

1. Move /dev, /tmp, /var/run, var/spool to ramfs (Uses approximately 18kb of memory depending on size of logs)

1. Need a mechanism to keep logs like the miau logs over time, but not write them to flash all the time, maybe save them upon shutdown or something? Yeah - I mave modified miau to put stuff in /var/spool - we should retain /var/spool over reboots - we have a rc.reboot diversion script facility.

1. Remount /share/flash/data -o noatime
2. Move /dev, /tmp, /var/run to ramfs (Uses approximately 18kb of memory depending on size of logs)

1. run swapoff -a to turn off swapping (Can we disable it just on one disk or the other?)

1. Need a mechanism to keep logs like the miau logs over time, but not write them to flash all the time, maybe save them upon shutdown or something?

Files that are modified in the last day on my slug:

/var/lock/samba/browse.dat
/var/log/messages
/var/log/messages.old
/var/log/samba/log.nmbd
/root/.miau
/dev/ptyp0
/dev/ttyp0\\

1. Move /dev, /tmp, /var/run to ramfs
2. /var/lock/samba and /var/log are already ramdisks

will turn off swapping

Files that are modified in the last day on my slug:

/var/lock/samba/browse.dat /var/log/messages /var/log/messages.old /var/log/samba/log.nmbd /root/.miau /dev/ptyp0 /dev/ttyp0

1. Remount root with -o noatime
2. Remount /share/flash/data -o noatime
3. Move /dev, /tmp, /var/log, /var/run to ramfs
4. Run swapon to disable swap device
5. These things would only happen if a file called /.flashroot existed with the current Unslung version number inside

1. remount root with -o noatime
2. remount /share/flash/data -o noatime
3. move /dev, /tmp, /var/log, /var/run to ramfs
4. Run swapon to disable swap device
5. These things would only happen if a file called /.flashroot existed with the current unlsung version number inside

both 1 and 2 above are accomplished by:
mount -o remount,rw,noatime /dev/root /
swapoff -a
will turn off swapping

1. Remount root with -o noatime
2. Remount /share/flash/data -o noatime

1. These things would only happen if a file called /.flashroot existed with the current Unslung version number inside

1. Remount root with -o noatime
2. Remount /share/flash/data -o noatime
3. Move /dev, /tmp, /var/log, /var/run to ramfs
4. Run swapon to disable swap device
5. These things would only happen if a file called /.flashroot existed with the current Unslung version number inside

Planned Implementations:

Planned Implementations:
These are mostly from TuneUnslungForUsbFlashDisk

1. remount root with -o noatime
2. remount /share/flash/data -o noatime
3. move /dev, /tmp, /var/log, /var/run to ramfs
4. Run swapon to disable swap device
5. These things would only happen if a file called /.flashroot existed with the current unlsung version number inside

Under Construction