|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
Does anybody have more technical info, or pointers to such, on the flash
file system used by the MERs? The reason I ask is that JPL's explanation for Spirit's problem states that mounting such a file system uses system memory proportional to the number of files in it - at least, that seems to be the leading theory supported by experimentation. It would be the first file system I know of with that property, but perhaps the requirement to reduce write cycles on the flash lead to it. It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. Jan |
#2
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
In article ,
Jan C. =?iso-8859-1?Q?Vorbr=FCggen?= wrote: ...It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. VxWorks is *not* an open-source system, so if the docs don't happen to discuss this issue... -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
#3
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
In article , Jan C. Vorbrüggen wrote:
Does anybody have more technical info, or pointers to such, on the flash file system used by the MERs? The reason I ask is that JPL's explanation for Spirit's problem states that mounting such a file system uses system memory proportional to the number of files in it - at least, that seems to be the leading theory supported by experimentation. It would be the first file system I know of with that property, but perhaps the requirement to reduce write cycles on the flash lead to it. It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. When your software is at Mars, you really don't have a very good way of debugging it. And it is rather common for filesystems to do this. It basically works like if you call opendir or readdir the kernel reads the inode for that directory. That inode contains "pointers" to all its files, if it's alot of files... it gets big. -- Vennlig hilsen/Best Regards Nils Olav Selåsdal NOS at Utel.no System Engineer UtelSystems a/s |
#4
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
Does anybody have more technical info, or pointers to such, on the flash
file system used by the MERs? The reason I ask is that JPL's explanation for Spirit's problem states that mounting such a file system uses system memory proportional to the number of files in it - at least, that seems to be the leading theory supported by experimentation. It would be the first file system I know of with that property, but perhaps the requirement to reduce write cycles on the flash lead to it. It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. Jan Someone posted these links on another group a week or so ago: http://www.windriver.com/products/true_ffs/trueffs.pdf http://www.m-sys.com/files/documenta...QRG_Rev1.3.pdf We know that they are using VxWorks, but whether they are using the M-Systems flashdisks, or some other linear flash technology is another question. The M-Systems devices unburden the OS considerably, but other flash architectures could certainly have an impact on system memory (RAM). Since the rover is not an open source project, the public is not invited to review the design. Any reputable RTOS (Real Time Operating System) vendor will specify memory requirements for their file systems. I am inclined to believe that the rover problem is subtle. For example, if there were a low priority process responsible for performing periodic integrity checks on all the files, a large number of files could have unforseen consequences. We (the public) just have to sit back and wait for Spirit to deliver its lesson on RTOS system design. Eric |
#5
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
Jan C. =?iso-8859-1?Q?Vorbr=FCggen?= wrote:
Does anybody have more technical info, or pointers to such, on the flash file system used by the MERs? The reason I ask is that JPL's explanation for Spirit's problem states that mounting such a file system uses system memory proportional to the number of files in it - at least, that seems to be the leading theory supported by experimentation. It would be the first file system I know of with that property, but perhaps the requirement to reduce write cycles on the flash lead to it. It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. I apologize for not having any technical data myself. However, I found that statement by NASA (more memory for more files) quite odd myself. Generally speaking, you want to keep the meta-data (filename, creation time, size, etc.) in the same non-volatile storage as the file itself. It is probably a matter of reporters not understanding technical issues the engineers don't fully understand (or can explain) themselves. James Graves |
#6
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
Henry Spencer wrote:
In article , Jan C. =?iso-8859-1?Q?Vorbr=FCggen?= wrote: ...It also seems strange that the MER software engineers have so little understanding on exactly how the flash file system works that they cannot say with authority whether this theory is correct or not. VxWorks is *not* an open-source system, so if the docs don't happen to discuss this issue... And the docs are not freely available either, AIUI. |
#7
|
|||
|
|||
VxWorks (?) Flash File System on the MERs
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
National Space Policy: NSDD-42 (issued on July 4th, 1982) | Stuf4 | Space Shuttle | 150 | July 28th 04 07:30 AM |
System to monitor heat panels could safeguard future spacecraft (Forwarded) | Andrew Yee | Space Shuttle | 0 | July 15th 04 06:14 PM |
European high technology for the International Space Station | Jacques van Oene | Space Station | 0 | May 10th 04 02:40 PM |
Spirit has a mind of its own? | Jon Berndt | Space Shuttle | 33 | January 28th 04 04:48 AM |
ESA Sees Stardust Storms Heading For Solar System | Ron Baalke | Science | 0 | August 20th 03 08:10 PM |