if /dev/sdb get full, /dev/sda must be sync before continue... it´s a background thread but it works like linux memory cache, but linux use ram (volatille) you want a volatille (ssd) it´s like this: http://www.seagate.com/www/en-us/products/laptops/laptop-hdd 2011/1/19 Roberto Spadim <roberto@xxxxxxxxxxxxx>: > yes, a jornaling but using ssd first and sata after > it´s not raid feature... > it´s per disk filesystem feature... > we could implement jornaling in raid too... > but´s more inteligent (easy) at application level (filesystem) > you could write first at network (if it´s faster than sata) and after > at sata (if it´s slower than network) > > it´s not a raid feature... it´s a per device feature got it? > maybe a device (not raid..) for a cache division on devices > for example > > > /dev/sda (sata 1terabyte 100mb/s) > /dev/sdb (ssd 1gigabyte 1000mb/s) > > /dev/cache_a (a mix of sata and ssd with sata size 1terabyte, and > mixed speed (memory, ssd, sata)) > > cache_a device should know that > early reads/write should be writen to sdb > time in time it should sync at sda > > the same happens with memory (ram memory) but it´s volatille (diferent > than ssd that´s not volatille) > > /dev/sdb should be sync > /dev/sda should be async (since /dev/sdb make it safe to use async) > > > that´s you intention? i don´t know if linux have it, anyone know? > > > 2011/1/19 Cory Coager <ccoager@xxxxxxxxx>: >> On Wed, Jan 19, 2011 at 02:16:08PM -0200, Roberto Spadim wrote: >>> ok, your hardware have: >>> cpu, memory, disk controller, disks >>> >>> and you computer have: >>> cpu, memory, disk controler (your hardware) >>> >>> if your computer cache don?t sync to your disk controller you will >>> lose information.... >>> >>> check that *memory, is the volatille memory and *disk controller is >>> the non volatille memory >>> if you tell me that you will never have a *memory, and you have always >>> a non volatille memory, no problem, you will never need a kernel >>> load... just a boot loader that read previous memory information and >>> start in that point... why don?t do this? non volatille memory is not >>> as fast as volatille memory >>> got the problem? >> >> Sorry, we're still not on the same page. I would use both a ramdisk >> and sata disk. The ramdisk would act as a persistent cache >> (with the battery) for the sata disks. Enabling write through >> would write to the cache first then sync to the sata disks. >> >> Understand what I'm getting at now? >> -- >> 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 > -- 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
