On Wednesday 26 October 2011 at 10:14 Dimitry Sibiryakov wrote: > Don't forget about the energy from rotating. In old HDD it was enough > for heads' parking. In modern models it may be enough for cache writing as > well.
I think that 'may be enough' is the problem. We just don't know. And it is not easy to prove, afaict. Well, other than running something like diskchecker (http://brad.livejournal.com/2116715.html) which is not something I'm in a hurry to do. Modern SATA drives often have 32MB of cache. Looking at some specs for Samsung drives they claim they can write 166MB/sec which would indicate that they could do 32MB in ~0.2 seconds. Is it reasonable to assume that the capacitors can manage this? Another thing that troubles me is Native Command Queueing NCQ). It seems to be on by default and I've never seen anything that allows it to be turned off. If the disc fails to write the cache during a power failure and NCQ is on then a corrupt database is highly likely. Everything really depends on the manufactures claims that the capacitors can flush the cache successfully. Can we trust them? Paul -- Paul Reeves http://www.ibphoenix.com Specialists in Firebird support ------------------------------------------------------------------------------ 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
