Date: Mon, 25 Jul 2005 07:57:19 -0700 From: Glenn Dawson <glenn@antimatter.net> To: FreeBSD Questions <ml.freebsd.questions@gmail.com>, freebsd-questions@freebsd.org Subject: Re: Dump/Tape block question Message-ID: <6.1.0.6.2.20050725074818.1abf71b0@cobalt.antimatter.net> In-Reply-To: <10549b08050725052035362ea8@mail.gmail.com> References: <10549b08050725052035362ea8@mail.gmail.com>
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At 05:20 AM 7/25/2005, FreeBSD Questions wrote: >Sorry if this is a repeat. I posted this on the 21st and never saw it show up >in the mailing list, so I'm assuming nobody ever received it. > >I have a question about dump and tape blocks. When I do backups, dump >tells me it uses a certain number of blocks for that particular >backup. I explicitly set my block size to 65K when I do a dump. When >I read the SCSI or hardware block location on the tape after the dump, >it's nowhere near the same number as what dump said it used. Assuming you're using the -b option, -b 64 will tell dump to write 64K at a time. When dump is done, and it tells you how many blocks it wrote, multiply that by 65536 and that will tell you how many bytes were written. -Glenn >How big is each block? I'd like to know about where on the tape I am >when I do an 'mt rdhpos' command (but I don't know how to determine >the reported block size), and I'd like to be able to calculate how >much data was written for each backup based on the number of blocks >dumped (I assume these blocks are the size I specify on the dump >command line). In fact, how can I calculate how many blocks my tape >can hold? (i.e. What is the biggest block number an 'mt rdhpos' or >'mt rdspos' will report for my tape?) > >Of course, an obvious solution to the last question is to write enough >data to fill the tape and then check the output of 'mt rdhpos'. I'd >rather not spend the hours needed and the unneeded wear on the tape to >figure that out. > >Kevin >_______________________________________________ >freebsd-questions@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-questions >To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org"
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