From owner-freebsd-questions Tue Jan 15 17:26:22 2002 Delivered-To: freebsd-questions@freebsd.org Received: from guru.mired.org (okc-65-31-201-166.mmcable.com [65.31.201.166]) by hub.freebsd.org (Postfix) with SMTP id 108AD37B402 for ; Tue, 15 Jan 2002 17:26:19 -0800 (PST) Received: (qmail 19124 invoked by uid 100); 16 Jan 2002 01:26:18 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15428.54969.119254.138926@guru.mired.org> Date: Tue, 15 Jan 2002 19:26:17 -0600 To: "Brian T. Schellenberger" Cc: questions@FreeBSD.ORG Subject: Re: HOWTO -- backup onto CDRs? In-Reply-To: <200201152209.g0FM9eI00811@i8k.babbleon.org> References: <15426.33499.296182.78699@guru.mired.org> <15428.29548.346178.21655@guru.mired.org> <57g057v1hx.057@localhost.localdomain> <200201152216.g0FMGjG00878@i8k.babbleon.org> <001601531120f12FE6@Mail6.nc.rr.com> <200201152209.g0FM9eI00811@i8k.babbleon.org> X-Mailer: VM 6.90 under 21.1 (patch 14) "Cuyahoga Valley" XEmacs Lucid X-face: "5Mnwy%?j>IIV\)A=):rjWL~NB2aH[}Yq8Z=u~vJ`"(,&SiLvbbz2W`;h9L,Yg`+vb1>RG% *h+%X^n0EZd>TM8_IB;a8F?(Fb"lw'IgCoyM.[Lg#r\ From: "Mike Meyer" X-Delivery-Agent: TMDA/0.44 (Python 2.2; freebsd-4.4-STABLE-i386) Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Brian T. Schellenberger types: > > > I did this all the time under Linux; even with a P-450 it worked just > > > fine as long as the system wasn't overtaxed (as in, load < 2), using the > > > stdin feature of cdrecord. I tried with burncd under FreeBSD and had no > > > success, though. Of course, cdrecord doesn't support stdin input so I > Drat. I meant "Of course, burncd doesn't support stdin . . . ." Use /dev/stdin as the file to burn. That works with burncd for me. Brian T. Schellenberger types: > On Tuesday 15 January 2002 02:48 pm, Gary W. Swearingen wrote: > > Anybody know what FS-specific (dump/restore) and non-FS-specific (tar, > > cpio, pax, afio) archivers SHOULD do with sockets and named pipes? (Are > > there any other kind of weird "files" besides those and block- & > > character-special files and symbolic links?) > Anyway, these are the only types of files that perl knows aobut; looks pretty > complete to me: There's one other type of screwy file: sparse files. These have "holes" where there are no blocks on disk. You can create one trivially: bash-2.05$ dd if=/dev/zero of=y oseek=1000 count=2 2+0 records in 2+0 records out 1024 bytes transferred in 0.000059 secs (17353403 bytes/sec) bash-2.05$ ls -l y -rw-r--r-- 1 mwm wheel 513024 Jan 15 19:19 y bash-2.05$ df . Filesystem 1K-blocks Used Avail Capacity Mounted on mfs:28 127023 111 116751 0% /tmp bash-2.05$ rm y So I now have a file 513K long that occupies 1K of disk space. In fact, the file is on a file system that's only 127K in size. The nasty part about sparse files is that there is no way to recognize them as such without examining the file systems internal structures. For instance: bash-2.05$ wc y 0 1 513024 y The system provides a block full of zeros for the blocks that are missing. Tar tries to recognize them as such. Cpio only does that if you use the --sparse option. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message