3 ms·
Any sufficiently complex system will always run in degraded mode, because the individual mtbf rates for distinct elements will compound. Even a stop-the-world o
by Joeri 9y ago
Any sufficiently complex system will always run in degraded mode, because the individual mtbf rates for distinct elements will compound. Even a stop-the-world overhaul can't fix that, it will reduce the failure rate but it won't get rid of it. The trick to running such a system is to assume it is broken and still figure out ways of providing continuous service.
- deleted 9y ago[deleted]
- sliverstorm 9y agoCase-study, large raid arrays. Last time I worked with one, it was exactly as you say, it was always degraded, and disks were constantly being replaced and arrays were constantly rebuilding.
- brianwawok 9y agoSo you fix the server case by a share nothing design. Put all data on 3 unrelated servers and query the fastest one. Not sure how you do this with subway tracks...
- couchand 9y agoWe'll just do the same thing. Call the three systems BMT, IND, and IRT.
- brianwawok 9y agoTouche! That raises the costs a bit though, if you actually had full service via 3 lines. Public transpo is already insanely expensive per rider over the 10-20 year term.
- Joeri 9y agoIt's not the track that breaks down, it's what runs on it. I don't see a reason why the electricity or signaling infrastructure can't be redesigned to have redundancies built in. If the aim with modernization is to replace old signals by new signals and still have just a single signal, that is still inviting calamity.