Could someone break down what is meant by root space? And how do I check mine etc...

Much appreciated!

The N900 has two (or three if you have a memory card installed) separate flash memory areas. The first is a 256M high-speed flash which is attached directly to the processor. The second is a 32GB built-in flash.

The root (or rootfs) is so-called because it's at the root of the directory tree (the lowest level). This is on the 256M high-speed memory, because it contains the libraries and applications that are used most often. The /home and the /home/MyDocs directories are on the 32GB internal memory - /opt is actually just a link to /home/opt.

The reason the root memory is only 256M is because that was the largest available at the time the phone was designed.

You can see what free space you have where by running X Terminal and typing:

So which figure should I be looking at? The line marked rootfs says it has a total of 227.6M. The line with a total of 256M is tmpfs.

Which one should I be worried about?

There's some rounding errors I think (or possibly binary vs decimal) - the rootfs line is the one you want to be worried about anyway.

Ahh. Then I should probably be worried. Which is slightly worrying as I have about 3 items from devel, all carefully checked.

How much free do you have? And have you rebooted after installing any apps?

Here's my df (diskfree) output. The parameter -h just means "human readable", which is Linux for "change bytes to megabytes and kilobytes and whatnot".

Our things of "interest" in this output are the first, next to last and last line.

We all have 227.9 megabytes of root file system available, but what's interesting is the "available" -column that says I have 34.6 megabytes or 85% in use.

The last two lines indicate that /home/user/MyDocs has a total of 27 gigabytes (with 17.3 gigs free) and /home (our home directory) has a total of 2 gigabytes (of which 1.7 gigs are still free).

This is called partitioning: The internal memory/drive has been divided into several parts, the most interesting of which are 227.9 megabytes, 27 gigabytes and 2 gigabytes in size.

These partitions can then be "mapped" (or mounted) to certain directories. That is why Linux lacks drives like windows (ie. C: and D. Instead, the physical disk or partition is mapped (connected, mounted) to a directory. So when Linux-guys insert a dvd, it doesn't become D: like on Windows. Instead it has to be manually or automatically mounted to a directory. That could be any directory, but usually ends up being something sensible like /mnt/dvd.

This is done to protect the system: We can fill up one partition and leave the other ones with plenty of space to function well. In the Maemo-case, the root mount is very small in size (228 megabytes) and should be left alone as much as possible. Instead, programs should be installed to the /opt -directory.

Interestingly, opt is part of the root filesystem! But if we look at /opt with ls, it says:

... which means /opt is actually a symbolic link to /home/opt. So /opt actually points to /home/opt, which has 1.7 gigs free, making it a good place to install apps.

Presumably the 18 megabyte download of today's new firmware release was significantly more when extracted. Upgrading stuff on Linux is often comparable to unzipping (extracting) packages on top of old versions (and maybe cleaning up the old versions before that). So the installer for today's firmware might have checked that it could fit completely on the rootfs. Let's say the unextracted firmware was 30 megabytes. The installer would then probably halt installation if less than 30 megabytes are available on the rootfs.

The installer is also probably not able to account for files that will be replaced (if we install a file that is 2 megabytes in size, we need zero megabytes of free space if this file replaces an older version that is also 2 megabytes. In fact, by installing the new 2 megabyte version of a file, we can INCREASE free space if we replace a more inefficiently compressed file that used to be 3 megabytes).

Sorry for writing so much, but you asked

I think you mean 85% used (15% available.)

I have about 80% used, with 45mb free. I guess I'm just one of those cautious people that likes to have oodles of free space 'just in case'. (My Girl guide training - always have food in the cupboard, a bit of money in the bank, a day or two of annual leave in hand and space on your drives. )

Since others seem to have the same or less, and aren't worried, I shall hereby stop worrying.

The Conky app brings up a list of system info. I had a look but it mut have been in one of the extra reps. Worth installing if you can.