On Sep 28, 2009, at 10:42 PM, Stefan Monnier wrote:
I have debian installed onto a 4gb usb stick (my laptops HD crashed and i'm using this as a temporary solution till i get it fixed). All works great. The only issue is that periodically, the whole system will freeze for 1-3 seconds and then come back. It doesn't matter ifI'm just doing some CLI stuff or using opera for web browsing. Happenssporadically and seemingly at random.What/where would I need to look on my system to possibly diagnose thisissue?It's a problem with the flash key (most/all flash keys suffer from thisproblem). It is also seen in many SSDs (it's a phenomenon referred to as "stutter"). There's not much you can do about it, IIUC. Stefan
The problem is essentially (it's actually a bit more complicated, but essentially) that the flash RAM fills up with un-erased pages and has to be garbage-collected. Because the flash controller doesn't know the details of the host's file system, it uses a naive brute-force garbage collection algorithm. Hence "stutter".
There's a protocol standards revision in the works, called TRIM, that will allow the host to tell the flash what parts of the file system can be erased and what it needs to keep. This will allow smarter garbage collecting, which can happen in the background.
Flash SSDs with the TRIM feature are planned to be available in 2010. It may take a while after that for Linux to be able to use it effectively.
I don't know what (or even "if") the time-frame will be for getting TRIM into USB sticks.
RickReference: http://www.anandtech.com/storage/showdoc.aspx?i=3631 "Understanding and Choosing the Best SSD"