Linpus bug in SDD expansion handling?

After downloading an application for later installation, I discovered that although I could see the installer in the Downloads folder via Thunbar, I couldn't find it in the terminal after navigating to the folder, even after typing 'ls-a'. Baffled, I suddenly remembered that I'd added an extra 16gb SD card to the expansion socket and thought that that might have something to do with it. So I uncoupled the card and looked again. This time, the installer was missing in Thunbar AND terminal. So I mounted the expansion drive via the SD slot and noticed that it contained a similar set of directories to the 8gb SDD and lo and behold, there was my installer! Because I have no idea how to navigate to a folder on an 'external' drive in terminal, I just moved it back to the SDD 's Downloads folder and ran it from there.

Seems as though Linpus has a problem seeing some files in the expansion space which could explain some other weird behaviour I've experienced since installing the expansion SD. For example, music files stored in the 'proxy' Music folder of the SD disappear from playlists between reboots. But at least I can still see those files in Thunbar and the Terminal. Anyone else noticed odd problems with Linpus folders after expanding the SDD?

 

Only Thunar makes use of the aufs filesystem, that "unites" the ssd and the left sd drives. Outside of Thunar at the command line, the sd is seen as a separate mount point, which indeed it is. The whole thing is a bit silly and confusing. It would have been nice if Acer had just avoided the whole thing and didn't try to unite the two drives. The only nice thing about the whole setup is that the left slot allows the SD card to get completely inserted and out of the way.

Cheers.

 

I've had exactly the same experiences as you have.I've downloaded files into My Music and My Downloads folders only to find that they've magically disappeared -- in fact they'd just been downloaded into the same named directories on the SDHC card in the left-hand expansion slot. It's rather annoying, as you would expect all files to be downloaded onto the SSD drive until all the space there has been used up.

 

That's interesting and explains the behaviour; but like you say, it's very silly, particularly if the Linpus OS (or Acer's implementation of it) cannot handle installer files correctly when an expansion card is installed. It would indeed be better if they were treated separately. Out of interest, is the storage expansion slot treated as a separate mount point if Windows is installed on the internal SSD?

 

Interesting comments. The use of aufs or unionfs to expand the filesystem is not unique to Linpus. Any of the distros on a Live CD that let you save your modifications to a USB stick do the same thing. I've been using Puppy Linux for a couple of years now, and it does this too. All of your additions/modifications go into a parallel directory structure that is overlaid on top of the original. The original remains pristine, but your changes take precedent. I don't know if Linpus keeps the original pristine when it can - it obviously doesn't (and can't) without an SD card in the expansion slot.

The way I normally use Puppy Linux, it's like having both the SSD and the SD card on the same USB stick. The advantage is that at boot time I get the option of using the expanded memory - it's not forced upon me.

If I choose to use the expanded memory, it behaves like pretty much like Linpus. I can get to the files in the expanded memory either by going to a special mount point or through the normal directory tree. However, I don't need to be running a filemanager (like Thunar) to access my files via the normal directory tree.

If I don't load the expanded memory at boot time, then everything that would go in the expanded memory is in a single file on my USB stick. That file internally contains a complete ext2-formatted filesystem (directory tree) with all of my changes. I can mount that filesystem on a loopback device at any mountpoint of my choosing to give me direct access to those files, and I can do this on any of my computers that run Linux.

I don't know if this will help explain what's going on or add to the confusion - hopefully the former. If the latter, I apologize.

 

The united filesystem is mounted at /mnt/home, which is what Thunar uses (and some other apps make use of it, Firefox at least), your home directory is /home/user which is what the Terminal uses. Someone here tried setting the home directory to /mnt/home and ended up with their AA1 not booting properly, now I believe this is down to /mnt/home not being set up before the user is logged in due to the early user login to get a quick boot, I suspect this issue could be resolved, but possibly at a cost to boot time.

 

Running applications from fat32 formatted SD card in left slot should be done from /mnt/home, since fat32 does not support ownership and executable flag.
If you like to change filemods for files on (fat32) SD card, go to /mnt/home/... (same subpath as /media/disk) and do
chmod a+x <filename>
which will be specially handled by posix overlay fs. You will realize some new files .povl or so being created at /media/disk/<subpath> indicating unix filemods to be used for this file on fat32 SD card.

Nevertheless, for some reason it is impossible to run apache httpd on an http dir located at /mnt/home/some/where (symlinked). This is the reason why I reformatted SD card to ext2, such making files directly executable or chownable at /media/disk and running httpd on those files. Reason: I'de like to keep my webpage stuff in homedir being backed up there with my other stuff.

I am not happy with this confusing and strange sandwich FS layout, especially since it does not work reliably. I know, the posix overlay stuff is necessary for running Linux on fat32 filesystems as like native FS. Only this way one can simply plug in some new SD card an work on it immediately without formatting it.

There is another issue with it: as soon as I plug in my external USB2 harddisk (fat32 at the moment, WD My Passport 250GB 2.5" drive):
1. /media/disk mount within homedir sandwich will fail and will no longer be available until reboot (that is, /mnt/home does only contain /home/user files)
2. posix overlay mount of /media/disk at /tmp/posixdir will disappear (anyway, would not be necessary with ext2 FS on SD card)
3. thunar filemanager pops up twice, 60 sec after plugging in HD
4. and eventually I found a kernel stack trace in dmesg output after plugging in external disk, making system freeze a short time later.

Thats not what I call clean FS management.
I will reformat HD to ext2 and see whether this will fix it.

These problems will not occur when using simple USB memory sticks (fat32 or ext2). This is a matter of the external harddrive only. I do not understand at all, what happens there. The external drive, needless to say, is working flawlessly on my wifes windows notebook. I do not believe there are issues with this special drive.
Regards, Phil

 

Could it be related to the presence/absence of a volume label? In Fedora, my USB sticks and SD cards with labelled partitions (FAT32 and ext2) mount at /media/volume-label. Does the FAT32 partition on your external HD have a volume label?

 

YES.
Reformatting drive (fdisk/mke2fs) fixed it. It is no longer mounted at /media/My Passport/
Startup ist much quicker, only one thunar popping up, posix overlay mount persisting.

Just bought another external drive, 500 GB, Seagate, preformatted for Windows, same issue here. Like the WD previously it has got some volume label under which it is mounted at /media. Plugging it into the Acer will bring up thunar twice, but currently there is no issue with the posix overlay.

Thanks a lot for helping!