there´s a forum (linux kernel) for ideas? 2011/1/19 NeilBrown <neilb@xxxxxxx>: > On Wed, 19 Jan 2011 18:13:23 -0200 Roberto Spadim <roberto@xxxxxxxxxxxxx> > wrote: > >> Hi guys, from a long email i will start this one: (the last one wasn´t send) >> >> think about this: >> >> /dev/sda (sata disk 1000gb size, latency of 1ms to move head, 100mb/s >> to write/read) >> /dev/sdb (ssd 1gb size, latency of <100us to find what flash and >> position, 500mb/s to write/read) >> ram memory (8gb size, with 1gb not used) >> /dev/mdxxx (the new device i´m calling it as raid0-cache) >> >> how raid0-cache work? >> >> >> how to create raid? >> tell what the sequencial read cache estrategy: >> memory(tell fixed memory size) - /dev/sdb - /dev/sda - another device >> (maybe just 2 is suficiente /dev/sdb and /dev/sda)... >> >> >> how to read? >> first, read from the first read device (memory) >> if information not there -> read from second read device (/dev/sdb), >> update information at first read device, return the read value >> if information not there -> read from third read device (/dev/sda), >> update information at second and first read device, return the read >> value >> >> how to write? >> flush space from first read device to second read device >> write to first read device, return OK >> >> background thread: >> sync from first write device (memory) to second write device (/dev/sdb) >> flush from second write device (/dev/sdb) to third write device (/dev/sda) >> >> startup: >> using cache: >> flush everythink from first write device (memory) to second write >> device (/dev/sdb) >> flush everythink from second write device (/dev/sdb) to second write >> device (/dev/sda) >> since memory is volatille, at startup it can´be flushed... >> without cache: >> make first write device unusable (memory) >> make second write device unusable >> here we can have write problems, since a wrong power off, can lost >> information from cache (first and second write device) >> >> >> >> anyidea who can make it? > > "Hey, I've got this clever idea, I wish someone would implement it" almost > always results in ... nothing. > People with the ability to implement are much more interested in implementing > their own ideas. > > But see also "bcache". > > NeilBrown > >> thanks >> -- >> Roberto Spadim >> Spadim Technology / SPAEmpresarial >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
