2) Not sure of your question. Linux will use the swap file as it sees fit. Nothing is guaranteed. Windows swapping has nothing in common with Linux kernel swapping.

1) Is it good idea to use swap file on USB flash? I have 32MB RAM and in most cases it is enough. I wonder how long time the flash memory will work when used for virtual memory.
2) If swap is used for heavy operation and then the necessary RAM fall in range of physical RAM - is it guaranteed that swap file will be freed and not used? For example in Windows I can have 3GB RAM, used 900MB and in most cases some small part of swap file is always used - no idea why.

swapon: /cifs1/E3000/opt/tmp/swapfile: Invalid argument

The CIFS is on a NAS with Ext3 partition, does any one has an idea what went wrong?
i used the dd if=/dev/zero to create the file and mkswap OK.

I am a new user (about 4 days) of TomatoUSB - Shibby build: [Tomato Firmware 1.28.0905 MIPSR2-070V K26 USB AIO Multilanguage] on ASUS-RT-N16.

I was following the tutorial on Optware Installation from tomatousb.org and googled information. I partitioned my usb hard disk to "Optware", "Swap" and "Data".

After rebooting, all is well except "Swap" was 'not active'. I googled and found this thread and read all the 3 pages as at this date.

Being a newbie, I am much overwhelmed.

I chose an easy way-out but not sure am I heading into a pitfall ahead.

What I did:
i) Add another line into [Administration]->[Script]->[Init:] and now my current setting as follows:

 echo "LABEL=Optware /opt ext3 defaults 1 1" >> /etc/fstab echo "LABEL=Swap swap swap" >>/etc/fstab 

I switched the router off and went for lunch. About an hour later, everything is still working when I power up the router.

Thanks in advance.

Bob

Update 20111106: Well, my original USB-HD went under. Was busy getting another 1 up again. The Swap is still working as expected, optware is installed and 'sftp' is activated by installing openssh-sftp-server using optware.
Update 20111231: Yes, it's kicking and alive! SFTP is working :) and Bittorrent - transmission is working hard for fun ;).

For a standard single swap use, and with no reboot (except problem) I used fstab method:
/dev/sda2 none swap sw 0 0
And it it works perfectly for me.

That is not safe and it is fragile. "Fragile" means that it will work until it doesn't.

In Tomato w/2.4 kernel it's not even right because there are no /dev/sdX's. Dunno about K2.6.

With current Linux kernels, the disk name (the X) are completely dynamic and depend on the order that the disks happen to be detected during bootup. On my Ubuntu system (kernel 2.6.32) the same disc gets different names each time I boot up. The exact same disk will sometimes be /dev/sda, sometimes /dev/sdb, etc. I have 4 disks and the only thing predictable is that they'll get names from sda to sdd. FWIW, one is a PATA disk and the other 3 are the same model of SATA.

Use LABEL= or UUID= instead of /dev/sdXN and it will work reliably.

/dev/sda2 none swap sw 0 0

And it it works perfectly for me.

i just ticked automount in usb section and message says
partition swap active
no need for scripting doctorate

I think that's only the case if there is a swap entry in the /etc/fstab.

i just ticked automount in usb section and message says
partition swap active
no need for scripting doctorate

thanks for the work you and teddy_bear put into the firmware; it is awesome!

Ditto!!!

Unless, of course, something has been swapped out. Cause swapoff pulls everything that it has swapped out back into RAM. And if the drive got yanked out, well it can't read anything from it, can it? So be prepared to cycle the router's power so it will reboot. ;-(

When you unmount via the GUI, it unmounts & swapoff's EVERY partition on the drive. It doesn't bother to look at fstab (since fstab could be lying)-it looks directly at what the kernel says. Which is /proc/swaps & /proc mounts.

Ahhhhhhh……..but maybe it doesn't do swapoff of swapfiles on a mounted partition. Haven't checked that.
Never checked that because a swap part is better than a swapfile, so I never use a swapfile. Certainly in 2.4, especially if the filesystem is ext3 (extra journalling, y'know). 2.6 claims that it does stuff special so that there is no difference.

[[edit]]
Boy are we clever! (teddy_bear & me)
It does work. It does swapoff on EVERYTHING (every swap thing) that is active on that disk. Doesn't matter if it's a mounted file partition, a swap partition, or a swapfile. If it's active, Tomato gets rid of it (umount or swapoff).

Wasn't specifically designed that way. The way we implemented it just automatically does everything right. I love it!
(Now I have to go to the the doctor, 'cause I think I sprained my arm patting myself on the back. ;-) )

 #!/bin/sh # $1 - The fully qualified path of the root directory of the mounted drive # (w/o any trailing '/'). # If no parameter, complain and quit. [[ xx == x$1x ]] && exit # Unmount the swap partition. SWAP_SPACE=`free | grep Swap: | awk '{print $2}'` if [ $SWAP_SPACE -gt 0 ]; then sed -i "/^LABEL=.* swap swap/d" /etc/fstab swapoff -a fi 

Which will run if unmount performed via web ui.

Always use the web ui/cli to unmount, never simply unplug. I have a script that initiates a clean swapoff but I don't use it as it is done under the covers.

How do you go about unmounting swap for rebooting and such?

Your solution worked perfectly. Thank you.

Install linux swap

dd if=/dev/zero of=/mnt/MyextHD/myswap.swp bs=1k count=64000 (create 64mb swap file at external hd MyextHD)

cd bin (go to root of router then change dir to bin-this is where busybox is located)
busybox mkswap /mnt/MyextHD/myswap.swp (setup swap file)
busybox swapon /mnt/MyextHD/myswap.swp (enable swapping on it)

That is it.

Thanks for the script ray123! I tweaked it slightly, hope you don't mind. :)

What changes did you make and how did they better server you?

Rodney

Timing, timing, timing. I HATE timing issues. Things work for a while and then something changes and suddenly they don't work.

1) Automount processes the partitions in numerical order.
2) When a swap partition is processed, it executes "swapon -a"
3) When a fat/ext partition is processed, it executes "mount", then executes the autoruns.

Here's the gotchas:
1) If the swap partition is after file parition(s), then you don't have swapping until after the file partition autoruns have been done. But what if one of those autoruns starts something that needs swapping enabled? Like a torrent client or mpd? Can you say, "Mysterious occasional lockup at startup?"
2) Mount can sometimes take a looooong time. Particularly when it's doing journal recovery on an ext3 partition that was not unmounted cleanly.
3) Busybox's "swapon -a" will choke if fstab has multiple SWAP entries and one of them isn't there. I made a patch for this that AFAIK is now in Tomato but isn't in the busybox distribution. I used to have several USB drives, each with a swap partition, and put them all in fstab. Worked fine, until the day when one drive was unplugged at bootup.

So, all in all, doing the swap in the autorun is much more bullet-proof than the fstab method. Much more robust at no additional cost.

LABEL=SWAP none swap sw 0 0

and then execute "nvram setfile2nvram /etc/fstab; nvram commit".

This prevents the need for any autorun script. :)

Rodney

Assign the swap and data partition a single-word descriptive label. For example use the label SWAP for the swap partition. The SWAPNAME variable in the script will have to reflect this label name.

2) Create the following script in the root directory of the data partition of the external drive, using vi, naming it "00-start-swap.autorun":

 #!/bin/sh # $1 - The fully qualified path of the root directory of the mounted drive # (w/o any trailing '/'). # See: http://www.linksysinfo.org/forums/showthread.php?p=364690#post364690 # The decriptive label assigned to the swap partition. SWAPNAME=SWAP # If no parameter, complain and quit. [[ xx == x$1x ]] && exit # Edit fstab to put the swap partition label there. sed -i "/^LABEL=.* swap swap/d" /etc/fstab echo "LABEL=$SWAPNAME swap swap" >>/etc/fstab # Activate the swap partition swapon -a 

Save the script and make it executable by issuing:

 chmod 0755 00-start-swap.autorun 

against the newly created script.

With the script in place in the root-directory of the mounted drive the swap partition will be mounted whenever the drive is plugged in.

The swap partition will auto-unmount when the drive is unmounted via the Tomato GUI.