| Line 21: |
Line 21: |
| | | | |
| | Discussions of Stick Failure and alternative file structures is now at [[Stick Layout]] | | Discussions of Stick Failure and alternative file structures is now at [[Stick Layout]] |
| − | ''Failure Modes''
| |
| − |
| |
| − | # Gets stuck at Fedora Login
| |
| − | ## With liveuser prefilled <br>I was able to repeatably create this failure when I was testing a version of schoolserver.py that had a typo in it.
| |
| − | ## With nothing prefilled <br> This error has successfully been replicated by Restarting multiple times.
| |
| − | # Bug in initramfs /init detected. Dropping to a shell. Good luck! bash: no job control in this shell. <br> Stick abuse, like putting it through the washing machine, seems to precipitate this type of failure.
| |
| − | # Freezes during use of an activity. Rebooting on the same computer doesn't help it still freezes on the same activity. One time we rebooted on a different computer and it worked.
| |
| − |
| |
| − |
| |
| − | We don't know the root causes but we have plenty of theories.
| |
| − |
| |
| − | Sticks will always fail. There will always be multiple causes for failure. This problem has to be addressed like a process engineering issue. Is stick failure a major cost in time or money? Find the largest cause of failure. Fix that to improve yield. Is stick failure a major cost in time or money? Find the the remaining largest cause of failure.....
| |
| − |
| |
| − | This summer we had probably 10 sticks fail for 35 students. That is a major cost in time and money. The most common unrecoverable failure mode was stuck at Login.
| |
| − |
| |
| − | ====We need a more robust files system====
| |
| − |
| |
| − | It has been shown that if you take a stick that is stuck at login and you copy over a fedora-overlay file from a working stick, the stick will boot again. Thus we are confident that the problem is corruption of the overlay file.
| |
| − |
| |
| − | ''Next Steps'' - Try some alternate file structures.
| |
| − |
| |
| − | # Create a Fedora Full Install USB Stick, restart it a bunch of times and see if it does better. How much space will the Fedora Full Install take?<br>So far its > 4GB http://wiki.sugarlabs.org/go/VMware#Full_Install_with_F11_Net_install_CD_to_USB_Stick
| |
| − | # Create an Open Suse USB Stick, restart it multiple times and see if it fails. How much space does it use?
| |
| − |
| |
| − | ''Background Links''
| |
| − | Thread from the Fedora Forum: [[http://forums.fedoraforum.org/showthread.php?t=221719]]
| |
| − |
| |
| − | Here is an idea for an alternative USB Format: [[http://wiki.sugarlabs.org/go/Sugar_on_a_Stick/USB_format]]
| |
| − |
| |
| − | Also see Ticket 907 [[http://dev.sugarlabs.org/ticket/907]]
| |
| − |
| |
| − | A 2 GB USB is about $.60 more then a 1GB stick. If we need to compress less to get robustness its ok for us to require a 2GB USB. A 4GB stick is about $2.50 more then a $1GB Stick.
| |
| − |
| |
| − | ''Theories that have evidence against them''
| |
| − |
| |
| − | Dave Bauer was able to replicate the failure easily by restarting a Sugar stick. This means its probably not:
| |
| − |
| |
| − | * The Bulk Copier, Dave doesn't have one.
| |
| − | * The older slower computers and USB 1 ports we are using at the GPA.
| |
| − |
| |
| − | ====Sticks are damaged during formatting or burning====
| |
| − |
| |
| − | http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device [[http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device]]
| |
| − |
| |
| − | There was a detailed discussion thread back in February at: http://lists.laptop.org/pipermail/devel/2009-February/022987.html
| |
| − |
| |
| − | If we understood how to win and we had our own stick creation activity perhaps we would have less failures.
| |
| − |
| |
| − | ====Sticks are of poor quality====
| |
| − |
| |
| − | Here is an explanation of two processes used to create USB sticks: http://www.solutiongrove.com/blogger/2008/09/08/there-are-two-type-of-usb-flash-memory-slc-and-mlc [[http://www.solutiongrove.com/blogger/2008/09/08/there-are-two-type-of-usb-flash-memory-slc-and-mlc]]
| |
| − |
| |
| − | ====Sticks are being improperly removed====
| |
| − |
| |
| − | Yes they are, but its not at all clear to me that that correlates with the sticks that are failing.
| |
| − |
| |
| − | ====There is a bug around restarting====
| |
| − | It is very common to fail after a restart, the system forgets its supposed to go to Sugar. See ticket 1069 [[http://dev.sugarlabs.org/ticket/1069]]
| |
| | | | |
| | ===Backup and recovery=== | | ===Backup and recovery=== |