FC5: High system load when copying data to slow USB media

[Robin Laing]

Boris Glawe wrote:
> Hi,
> 
> I have a problem with my 2GB Memory Stick Pro Duo Card. The card itself 
> is an orginal MemoryStick PRO Duo from Sony.
> 
> I am using this card in my cell phone. The phone is a Sony Ericsson 
> W810i, which is capable to appear as an usb mass storage device. I also 
> have an USB 2.0 card reader. The problem described below happens with 
> both the card reader and the cell phone.
> 
> My problem is, that copying large amounts of data (a few hundred MBs, 
> for example) to that device causes the system load to increase to almost 
> 100% and, under certain circumstances, to lock my desktop from time to 
> time during the copying process. It is normal that copying takes very 
> long, as the card itself is very slow in writing, but the high system 
> load in combination with the lack of responsiveness of the whole system 
> seems to be a bug!?
> 
> In addition to this problem, copying data to such a device is very opaque:
> A copy command on either the terminal or the nautilus gui, immediately 
> terminates successfully, though the data has not really been written to 
> the card, yet. This asynchronous behaviour is ok for performance issues, 
> but one doesn't know when the card can be unmountet. I actually know 
> what to do: I run the command sync and as soon as this commands 
> terminates, I know that the cache is written to the card. Problem with 
> this: When sync executes, the system load increases even more and the 
> desktop is much more often locked, then it would be without having 
> executed the sync command. The system stabilizes, as soon as the cache 
> is written to the card.
> 
> Unounting the card with the Gnome gui make things even stranger. Gnome 
> obviously seems to unmount the card though the cache has not been 
> written yet (the symbol disappears from the desktop), but comes back 
> after about 30-60 seconds with an error message, that the card cannot be 
> unmountet (One usually uses this time to remove the card from the 
> reader) This unmount command triggers a sync, of course, which again 
> results in the same behaviour as described in the paragraph above, when 
> running sync manually.
> A "df -ah" on the terminal results in a "/media/disk not found" message, 
> then.
> This is one of the reasons why it would be very nice to at least know, 
> when the device can be unmountet.
> 
> Can you confirm the problem with the high system load and the lack of 
> responsiveness when copying large amount of data to a slow USB mass 
> storage device, like my 2GB memory stick pro duo?
> 
> Thanks for any hint and comment
> 
> greets Boris
> 


The syncing/unmount is a bug and is being worked on.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=194296

I had a major problem with a trashed file system on a memory card due to 
this bug.

---

On my machine.

$ time { cp *.mp3 /media/music/; sync; }
real    14m35.521s
user    0m0.192s
sys     0m4.500s


160 files
775M
.89MB/sec.

No real load on the rest of the applications.

2Gig ram


-- 
Robin Laing