On 10/26/11 14:26, Lester Caine wrote: > Paul Reeves wrote: >> Everything really depends on the manufactures claims that the capacitors can >> flush the cache successfully. Can we trust them? > It's not just the drives capacity that matters here. Most of the machines > I've > checked will continue to run for several seconds after mains is removed > simply > due to the 'capacity' in all the power supply stages. It's telling the OS to > stop that is the real problem here and not one that current systems provide > for ;) > > But really all 'critical' machines should have some sort of UPS, either on > board > the machine or an external UPS which can close down the machine cleanly. I > don't > think one can 'design' relying on some arbitrary effect? Certainly all my > critical ones have their own UPS box. >
Unfortunately there are at least two problems with relying only on UPS. First of all any other element in machine can get damaged, starting with CPU. Certainly, this does not prevent HDD to flash it's write cache, but setting FW=ON is very useful from this POV. And the second one is when UPS itself dies. I've seen myself such cases when getting serious pulses in the power supply UPS turned off itself at all, blinking with LEDs 'Unknown error' message. (People avoided that problem only by installing good filter before UPS.) And yes, taken such UPS together with fcntl() linux bug (that was in 1.5 epoch) database got damaged. > Aside from that, I am wondering if this write processing is part of the > explanation of the performance differences between Windows and Linux 'web > stacks' on the same hardware. I'm seeing W7 setup 4 times slower than the > same > stack running on SUSE 11.4 which is dual boot installed on the same machine. There may be many reasons, but this one is very possible. ------------------------------------------------------------------------------ The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
