Date: Thu, 1 Feb 1996 08:24:32 -0800 (PST) From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com> To: stesin@elvisti.kiev.ua (Andrew V. Stesin) Cc: hackers@freebsd.org, ccd@forgery.CS.Berkeley.EDU Subject: Re: Am I root?! or How to mirror an 'a' partition? Message-ID: <199602011624.IAA20540@GndRsh.aac.dev.com> In-Reply-To: <199602011355.PAA15508@office.elvisti.kiev.ua> from "Andrew V. Stesin" at Feb 1, 96 03:55:18 pm
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> > That was an announcement of new ccd driver and it's mirroring > capabilities. I'd be _glad_ to test it, but I'm afraid it > won't mirror an 'a' partition, and in case one disk will > _totally_ go south late at night, it will wait for > manual intervention anyway (i.e.: sd1 will become sd0 after > panic -> 'sd1: device not configured' or whatever -> waiting > for me to come and repair the box). ... > dd if=/dev/rsd0[efg] of=/dev/rsd1[efg] bs=64k > > work fine, but > > dd if=/dev/rsd0a of=/dev/rsd1a bs=64k > > bombs and tells me: "dd: /dev/rsd1a: read-only filesystem"? > sd0a is mounted on / and sd1a isn't mounted at all. Because the first 16 blocks of the a partition are special, they contain the bootblocks and disklabel. These are protected from writes and require a special ioctl to be able to write them. > > dd if=/dev/rsd0a of=/dev/rsd1a bs=16b skip=1 Try adding a seek=1 so you skip over the first 16b of the output device too. Skip only effects the input file. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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