Transferring the root filesystem to a ramdisk?
julian at elischer.org
Sat Jan 31 08:47:47 PST 2004
On Sat, 31 Jan 2004, Bjorn Eikeland wrote:
> I'm probably in over my head here, but;
> chroot should change the root filesystem for you.
> (look in the manpages for more details)
> As for powering down the hdd I did find a page for this,
> but havent had time to play with it yet:
there is a port "ataidle" that sets teh IDE drive's internal idle
timeout timer so it will spin down if you dont use it..
as for scsi, you can sent it a spin-down command with camcontrol but I
forget the actual command..
(it should be in the scsi .h files)
> best of luck!
> > 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.
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