Date: Fri, 12 Dec 2003 17:02:16 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Jonathan Wright <wrightcs@comcast.net> Cc: freebsd-questions@freebsd.org Subject: Re: tar, mt backup BLOCKSIZES, variable & fixed question Seagate SDT224000N DDS-3 DAT Message-ID: <20031212230216.GB17799@dan.emsphone.com> In-Reply-To: <5.0.0.25.2.20031212153110.02916768@wheresmymailserver.com> References: <5.0.0.25.2.20031212153110.02916768@wheresmymailserver.com>
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In the last episode (Dec 12), Jonathan Wright said: > up" if there is a delay in the host computer's data access. However, > I am getting inconsistent information on the variable blocksize > setting in mt and don't know if I should use it or not. One site I > found said that variable blocksizes allow the drive to write blocks > at a size that it thinks will be best for the data speed at hand, > while another site said that it allows the drive to use the blocksize > being sent to it from the backup application (making 10,240 byte > blocks in the above tar example). Who is right, or have I got this > all mess up? :) variable blocksize means write data to tape using whatever size chunks the user write()s. I think only ancient QIC tapes actually need you to set a fixed blocksize via mt. > Also is there a preferred blocksize for DDS-3 DAT drives? I use 64k for everything. -- Dan Nelson dnelson@allantgroup.com
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