Date: Sat, 31 Jan 2004 15:08:33 +0100 (CET) From: Cordula's Web <cpghost@cordula.ws> To: freebsd-questions@freebsd.org Subject: Transferring the root filesystem to a ramdisk? Message-ID: <20040131140833.69B9540823@fw.farid-hajji.net>
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Hello, in an attempt to save power on FreeBSD servers, I'm trying to replace the hdd with a ramdisk. The idea is to: 1. boot from the hdd (or netboot from an NFS server) 2. configure a ram disk (md(4)) 3. copy everything that's needed to ram disk 4. transfer kernel root to ramdisk (*) 5. turn off the hdd (**) (*) is the hairy question. (**) How can that be done? I won't need paging, because there'll be enough ram for everything (ramdisk, kernel and userland). Now the questions are: * How to "attach" the root filesystem to the ram disk? Can this be done only through pxe/netboot before the kernel starts, or is there some kind of system call that can transfer root on a running system? * How to power off (and on) the hdd (both for ATA and SCSI)? * Will the power consumption decrease (no hdd) or will it increase (more ram)? Anybody measured this before with regular diskless machines? Thanks, -cpghost. -- Cordula's Web. http://www.cordula.ws/
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