Ext Woes

[Pleng]

I am crrently toying with using an ext file system on my 32Gb SD card.

Unfortunately often after resetting or shutting down with XFCE running, my first (ext) SD card is not mounted. I have to manually mount it by going into thunar and clicking on it. This has various side-effects some managabe some not so much.

A small issue is that minimenu looses its skin and menu configs until the card is mounted. No big issue.

The biggest, unmanagable issue is that after mounting the card, firefox crawl as the SD card is hammered with activity. Presumably checking the files that are being accessed. But it takes a couple of minutes to load fast dial and chokes when loading a page.

Additionally SNES9x and PicoDrive take several minutes to display their ROM directories.

And unfortunately these problems usually last for 2 or 3 times of running the programs. I don't think it's due to a file check being performed in the background as I left my unit on overnight after the last occurrence and still had the issues the following morning. Also the access light doesn't flicker unless an app is launched.

I run my system at 800Mhz pretty much consistently (aside from when the lid is closed - then it's set to 125).

Should I just move back to FAT32??

 

[Prometheus]

Which ext are you using?

If it's of any help, I use ext2 on all but two of my cards, and I formatted them using KMFormat on my old Kubuntu setup (KMFormat just calls the standard terminal commands, though - I'm just mentioning this for completeness' sake; I recently moved to Xubuntu 10.04 and haven't done any messing with card formatting here yet), and haven't had any problems, no matter how I'm using my Pandora.

 

[Pleng]

I can't remember if I used ext2 or ext3 to be honest. Anf I don't have access to a linux box to use kde tools either.

 

[Prometheus]

How did you format the cards as ext-whatever, out of curiousity?

(If you're not command-line shy, I wonder if they can be formatted on the Pandora itself with a quick copy-and-paste of what you'd have to do? Just throwing out an idea which I can't check the viability of, since I'm currently still sans Pandora. )

 

[urjaman]

Yeah the pandora has mkfs.ext2 / mke2fs and fdisk like you would expect, so doing partitioning & formatting stuff is possible. It is by default missing mkdosfs, though... (Thats an opkg install away).

 

[Pleng]

How did you format the cards as ext-whatever, out of curiousity?

(If you're not command-line shy, I wonder if they can be formatted on the Pandora itself with a quick copy-and-paste of what you'd have to do? Just throwing out an idea which I can't check the viability of, since I'm currently still sans Pandora. )

I used whatever command was shown in the 64Bg SDXC thread in general talk

 

[Prometheus]

This one? Looks like it's ext3, then.

EDIT: I'm just having a read of this, and this just caught my eye: "If called as mkfs.ext3 a journal is created as if the -j option was specified. ".

 

[paulguy]

Could using ext2 be the reason for poor performance with my 32gb card? I should try the panasonic formatter and see if things improve. I'd really like to use ext2 on it though so I can use it as a rootfs.

 

[Prometheus]

I'm not having any performance issues with ext2 on my main card (a 32GB Verbatim card, Class 6), or on any of my secondary ones (an assortment of Play.com own-brand 16GB Class 4 ones), personally. What's poor about the performance?

 

[Pleng]

OK is there any way to turn on-the-fly file checking off for ext3? As I'm pretty sure that's the problem. Otherwise it's back to lovely Fat32 for me. I just tried Mupen64 for the first time since my last 'problem'. I had to wait 3 minutes for it to load, and even after it loaded the SD light was flickering like mad. I got half way through a very stuttery lap and all of a sudden, as the SD light shone ever brighter, my framerate dropped to something like 3 seconds per frame!

Lucky I was alone... would have been embarrassing if I was showing off Mario Kart to demonstrate the Pandora's power!

 

[Prometheus]

Short of reformatting, I'm honestly not sure - but bear in mind that I'm not super-ultra-technical so there probably is a way, but I just don't know it.

 

[cosam]

OK is there any way to turn on-the-fly file checking off for ext3? As I'm pretty sure that's the problem.

Not sure what you mean exactly but most parameters can be changed using tune2fs. Personally I would drop the journaling on an SD card.

 

[Pleng]

I'm not sure what I mean exactly either! It seems that generally after the card is (for whatever reason) unmounted by the system - or not mounted on startup, any time a file or directory is accessed the first time the sd card gets hammered. I'm presuming that the files are being checked for errors or something in the background. Is that what the journaling is? If so, how do I switch it off?

 

[cosam]

It sounds a bit like a filesystem check is running in the background, although I'd expect that to start right after the mount. Do you see any fsck processes running when this happens? If so, this can be disabled using tune2fs, although the risk of a corrupt filesystem is obviously increased. Maybe also try a manual fsck (with the card unmounted) to see if there are any inconsistencies.

But no, this isn't journaling. Journaling helps recover a file system if it's uncleanly mounted without having to do an fsck. Sounds ideal in this case, but it comes at the expense of causing extra writes which may prematurely wear out solid state media. But lets not start another debate about that again...

 

[Blue Ion]

If I recall journalling on the ext3 can't be turned off, at most, it can be changed to writeback mode where it is journalled as little as possible. That is a new feature from ext4, the ability to turn journalling off.

However, I've been running ext3 for quite some time on the pandora and perfomed just as well, on a 16 gb class 6 Transcend card, and if defaults of many linux distros are maintained, ext3 used the ordered mode of the journal (helping me to dodge many bullets from accidental ejects, crashes and the like).

If I boot with the card plugged in, the OS will check it for errors if it is necessary and automount it when xfce starts.

Keep in mind that journalling is only there for writes, so there shouldn't be any perfomance penalty when reading

I don't really know what is making it so slow, you could try doing a "lsof | grep /path/to/your/card" to see who is accesing it. Also you might want to check the filesystem integrity explicitly, ie, using "fsck -f". It happened to me with normal hd as well, that journalling didn't catch errors on the hard disk and only appeared on a explicit check.

 

[Pleng]

I can't umount the card - I get device busy errors.

I don't believe it's a filesystem check happening in the background as the problem dissapears once an app has run two or three times since the unclean unmount, but for that app only. It's been two weeks since the last incident occurred and all apps I've run since then have been fine. I loaded up Mupen64 today for the first time since the last issue and I get the problem reoccuring. So it looks like any check that may be happening is only happening at the point a directory is being accessed, not the whole cared at once - and I have no way of forcing a full check either to eliminate that possibility.

lsof | grep /media/APPS produces no lines of output whilst idling and I've run mupen64 enough times now for the problem to go away and I can't think of any other app that hasn't been used!