Date: Mon, 21 Dec 1998 09:29:08 -0700 From: Tim Jones <tjones@estinc.com> To: Dag-Erling Smorgrav <des@flood.ping.uio.no> Cc: "Jordan K. Hubbard" <jkh@zippy.cdrom.com>, Matt Jacob <mjacob@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/sys mtio.h Message-ID: <367E7753.B8CAB53E@estinc.com> References: <82280.913951353@zippy.cdrom.com> <367A7E50.B0F5AA3B@estinc.com> <xzp7lvlfw17.fsf@flood.ping.uio.no>
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Dag-Erling Smorgrav wrote: > > Tim Jones <tjones@estinc.com> writes: > > So that everyone understands, the next version of BRu for Linux will > > offer Quick File Access. This means that the user can say "Restore > > mydatafile.dbf" and BRU will fast forward the tape to the appropriate > > logical block address and restore the file. This means a file 2GB deep > > on a DAT tape will restore in 30 seconds, instead of 45 minutes. > > Will this also speed up 'mt [fb]s[fr]'? Hi DES, This will be dependent on the tape drive used. If a 4mm DDS or 8mm drive, then it will definitely speed things up as the command to implement the motion command (SPACE - command 0x11 or (on older Archive and Wangtek 1/4") SEEK BLOCK - command 0x0C) use the drive's high speed wind functions. However, my tests here indicate that the 'mt fsf' when applied to my DDS-2 HP drive works as it should (takes around 15 seconds to get in 400MB or so). Be aware that linear tape drives (1/4", Travan, et al) will always be slower than this since seek speed is only slightly faster than normal read speed. For example, the new NS-8/NS-20 drives spin tape at 100ips for normal read/write, but the fast seek speed is only 120ips. -- Tim Jones tjones@estinc.com Vice President Visit our tape backup web pages: Enhanced Software Technologies, Inc. http://www.estinc.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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