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Xref: sserve comp.sys.ibm.pc.hardware.storage:13484 comp.periphs.scsi:26442 comp.sys.next.hardware:13610 comp.os.linux.misc:29316 comp.os.linux.help:64600 comp.os.386bsd.misc:4036 comp.os.386bsd.questions:14344 Newsgroups: comp.sys.ibm.pc.hardware.storage,comp.periphs.scsi,comp.sys.next.hardware,comp.os.linux.misc,comp.os.linux.help,comp.os.386bsd.misc,comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!uwm.edu!cs.utexas.edu!howland.reston.ans.net!pipex!uunet!virtech!aib.com!not-for-mail From: eric@aib.com (Eric Youngdale) Subject: Re: SyQuest SQ3270S for Data Exchange? Message-ID: <39rphi$23o@esp22.nrl.navy.mil> Lines: 33 Sender: news@aib.com (Usenet/NetNews Administrator) Nntp-Posting-Host: andante.aib.com Organization: AIB Software Inc References: <CyrtGF.2u4@prz.tu-berlin.de> <39m6eh$hts@news.cc.utah.edu> Date: Thu, 10 Nov 1994 00:29:38 GMT In article <39m6eh$hts@news.cc.utah.edu>, Terry Lambert <terry@cs.weber.edu> wrote: >You should be aware that Linux, if you choose it as a platform, has >some cache code discrepancies that I don't quite trust when it comes >to removable media. It doesn't flush the cache on a removable volume's >data when the volume is removed. There is a finite probability for >error in doing this. This is not as much of a problem in CDROMs, but >for writable media it could quickly become a problem. > >The tagging mechanism is similar to IBMs JFS, which (incorrectly) assumes >that a removable volume will be remounted in the same drive it was first >created in. Multiple drives will drive it nuts, since it assumes the >drive idenitifier as part of the unique ID for the volume. Huh??? This is nonsense. If you remove a scsi disk and re-insert it, the disk will report UNIT_ATTENTION the next time you attempt to access it. The scsi disk drivers notice this, and automatically invalidate all of the buffers associated with the drive. Inodes are automatically flushed when a device is unmounted. This is because you could umount, make a new filesystem and remount, and the cached inodes would be incorrect. >This is especially evident if you are trying to do CD mastering with a >R/W ISO9660 volume and a CDROM one-off and both are on removable media. Irrelevant. The drive will report UNIT_ATTENTION and the buffers will be flushed. Non-scsi devices, such as a mitsumi, also report disk change, and the buffers are similarly flushed when the media is changed. -Eric