Date: Tue, 03 Mar 1998 12:22:59 -0800 From: Julian Elischer <julian@whistle.com> To: shimon@simon-shapiro.org Cc: hackers@FreeBSD.ORG Subject: Re: SCSI Bus redundancy... Message-ID: <34FC66A3.2781E494@whistle.com> References: <XFMail.980303121451.shimon@simon-shapiro.org>
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Simon Shapiro wrote: > > I have seen an interesting solution some time ago; Instead of battery, the > spindle motor (on the disk) was used to generate the power needed to flush > the caches. then the motor leads will be clamped, and the spidle shut down > quickly (normal procedure nowdays). This was done on a 14" spindle that > had a bit more inertia than todays' disks. But the circuitry consumed more > power too. > spindle inertia is no longer used for power. I quote from the Qantum fireball programmer's manual.. "You may apply the power in any order, or open either the power or return line with no loss of data or damage to the disk drive. However, data may be lost in the sector being written at the time of power loss." Other drives have similar stories to tell. We queried the manufacturers closely on this and they confirmed that they cease all operation IMMEDIATLY on recognition of power loss. julian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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