NASA rover reboots twice over Easter weekend |
NASA rover reboots twice over Easter weekend |
Apr 14 2009, 12:47 AM
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#1
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Martian Photographer Group: Members Posts: 352 Joined: 3-March 05 Member No.: 183 |
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Apr 14 2009, 06:04 AM
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Member Group: Members Posts: 184 Joined: 2-March 06 Member No.: 692 |
One hopes that Spirit isn't seeing some wear and tear from the computer doing very many reboots at the start of its mission. Didn't Spirit just have some computer issues before the latest software upload?
And how does this effect Oppy. Does it stand down to see if a common software bug could effect it? Brian |
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Apr 14 2009, 02:06 PM
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Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
One hopes that Spirit isn't seeing some wear and tear from the computer doing very many reboots at the start of its mission. Didn't Spirit just have some computer issues before the latest software upload? And how does this effect Oppy. Does it stand down to see if a common software bug could effect it? Brian I am on vacation this week (Spring Break with my kids in the PNW) so I do not know what's going on on at Gusev. I know Opportunity is driving (forwards!!). Related to computer booting: I don't think that adds wear and tear. I know of a company that built an empire around computer rebooting. Paolo -------------------- Disclaimer: all opinions, ideas and information included here are my own,and should not be intended to represent opinion or policy of my employer.
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Apr 14 2009, 03:59 PM
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#4
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
I don't think reboots should affect much but Flash memory does degrade with use. It takes a while but we are running into fairly large data volumes for the lifetime of the rovers. I'm pretty sure that the type of Flash memory used in the MER's is good for around 100k write cycles per cell but five years with a few tens of GB of data throughput in the relatively harsh environment of the Martian surface might be enough to start seeing more frequent transient errors if there was any significant "hotspot" on the Flash drive that was getting a lot more write activity than the average. However I suspect that if this was the root cause Opportunity would be more likely to exhibit the problem as I'm pretty sure she has delivered more data - and given the use of deep sleep mode any wear that was related to the boot process should also hit Opportunity sooner than Spirit since the former has made much more use of that than Spirit IIRC.
Here's hoping it was just some freak occurrence of cosmic ray hits. |
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Apr 14 2009, 04:41 PM
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#5
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Senior Member Group: Members Posts: 1585 Joined: 14-October 05 From: Vermont Member No.: 530 |
I don't think reboots should affect much but Flash memory does degrade with use. It takes a while but we are running into fairly large data volumes for the lifetime of the rovers. I'm pretty sure that the type of Flash memory used in the MER's is good for around 100k write cycles per cell but five years with a few tens of GB of data throughput in the relatively harsh environment of the Martian surface might be enough to start seeing more frequent transient errors if there was any significant "hotspot" on the Flash drive that was getting a lot more write activity than the average. Even if the memory doesn't use the algorithms that balance write cycling (and flash architecture usually needs only balance by sectors or pages or whatever the minimum memory chunk is that can be erased before reprogramming, not by individual bit), it's worth bearing in mind that, like a rover with a 90-day guarantee, each individual flash cell has a 100k (or more) guarantee, but the average flash cell will achieve far more than that. And if there is overhead in the ECC, a single bad bit isn't going to kill the word. |
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