From owner-freebsd-hardware@FreeBSD.ORG Mon May 30 16:26:37 2005 Return-Path: X-Original-To: freebsd-hardware@freebsd.org Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2384116A41C for ; Mon, 30 May 2005 16:26:37 +0000 (GMT) (envelope-from tuliogs@pgt.mpt.gov.br) Received: from mitra.mpt.gov.br (mail.pgt.mpt.gov.br [200.157.62.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2E8AF43D1F for ; Mon, 30 May 2005 16:26:33 +0000 (GMT) (envelope-from tuliogs@pgt.mpt.gov.br) Received: from [10.0.0.136] (516e.pgt.mpt.gov.br [10.0.0.136]) by mail.pgt.mpt.gov.br (8.13.1/8.13.1) with ESMTP id j4UGQXIQ097289 for ; Mon, 30 May 2005 13:26:33 -0300 (BRST) (envelope-from tuliogs@pgt.mpt.gov.br) Message-ID: <429B3EC6.7000905@pgt.mpt.gov.br> Date: Mon, 30 May 2005 13:26:46 -0300 From: =?ISO-8859-1?Q?Tulio_Guimar=E3es_da_Silva?= User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-hardware@freebsd.org References: <428CF20F.50607@pgt.mpt.gov.br> <428D0D79.7010506@rcn.com> <428DFF35.1000409@pgt.mpt.gov.br> In-Reply-To: <428DFF35.1000409@pgt.mpt.gov.br> Content-Type: multipart/mixed; boundary="------------070700020304090207080403" X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Re: Weird behaviour of AIT-3 and (g)tar X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-hardware@freebsd.org List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 May 2005 16:26:37 -0000 --------------070700020304090207080403 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by mail.pgt.mpt.gov.br id j4UGQXIQ097289 Up and again, a little more testing showed that "compression enabled" is slower and=20 fits *less* data than having it disabled. I dumbly didn=B4t save the screen results, but I can repeat the tests=20 and post the exact messages, if needed. For now, what I can say is=20 compression dropped the transfers from about 11,8 MB/s to 10MB/s and=20 reduced the capacity from about 95GB to 85GB. I repeated 2 times each=20 test, with little variation, and maintained block sizes of 64kb,=20 filtering with dd: To store: # dd if=3D/home/bkp/backup_050425.tar of=3D/dev/esa0 bs=3D64k To restore: # tar -b 128 -xvOf /dev/esa0 | dd of=3D/dev/null Note: I don=B4t know if the tape rewinding+ejection time counted in the= =20 total time. I used /dev/null to be sure HD performance would not=20 interfere. In fact, writing to the tape was about 1% slower than reading. Would this be expectable? Tulio Tulio Guimar=E3es da Silva wrote: > Hi Gary, > ouch! That=B4s quite disappointing... :( We had already noticed this=20 > kind of behaviour with DDS-* tapes, but we got some progress varying=20 > the block size... and yup, I=B4m really using gzipped data. :S > For AIT-3, however, i thought this hardware compression was something=20 > about using lower tape=B4s phisical-rolling speeds or alikes, but I=20 > could never really find anything concrete about the methods... the=20 > only one thing I found was they could use "variable block sizes", but=20 > that=B4s all. Again, not many details. Anyway, I=B4m giving up the idea= of=20 > compression for now. > If something, I=B4m noticeing that (at least with -b 10) it becomes (a= =20 > lot) slower with time, but I guess this would be more of a question to=20 > the -performance list. > Add: while writing this message, I remembered to check the 700V=B4s=20 > "Product Specification Manual", and they mention something about=20 > dual-partitions, but it seems something that needs to be implemented=20 > at driver level, since it includes SCSI commands. In this case, I=20 > would need to format the tape as a 2-partition one... any clue about=20 > if and/or how that works on FreeBSD? > Thanks again, > > Tulio > > Gary Corcoran wrote: > >> Tulio Guimar=E3es da Silva wrote: >> >>> Hello again, >>> >>> I=B4m having some trouble putting a Sony SDX-700V SCSI AIT-3 unit=20 >>> to work on FreeBSD 5.3-RELEASE. >> >> >> ... >> >>> Besides the speed, hardware compression seems to not being=20 >>> funcional either. I already tried every 4 possible dip switch=20 >>> setting for compression, but I am still not able to transfer a 180GB=20 >>> archive to a (should-be) 260GB medium. >> >> >> >> I can't help you with most of your problems, but regarding the=20 >> "compression"... >> >> I would guess that if you have 180GB to backup, it's not all text. :) >> When I last used a tape drive years ago, when writing to a 2GB tape >> that would supposedly hold 4GB compressed, I could fit only about 1.9G= B >> before the tape was full. Turning off hardware compression, I could f= it >> 2GB. The problem was that I was saving already compressed multimedia=20 >> files, >> and the tape drive's "compression" just added overhead and took up=20 >> more space. >> So unless you're backing up text or similar files, don't believe the >> marketing hype about getting 2x the amount onto your tapes... >> >> Gary > > >------------------------------------------------------------------------ > >_______________________________________________ >freebsd-hardware@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-hardware >To unsubscribe, send any mail to "freebsd-hardware-unsubscribe@freebsd.o= rg" > =20 > --------------070700020304090207080403--