Date: Sat, 17 Dec 2005 19:00:00 -0500 From: "Dan Langille" <dan@langille.org> To: freebsd-scsi@freebsd.org Subject: no tape - ENXIO - device not configured Message-ID: <43A46030.31260.5B3110E@localhost>
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You probably know that I'm a developer on the Bacula <http://www.bacula.org/>; project. One of the issues we're trying to improve now is using the tape drive when there is no tape. Basically Bacula needs to open() the tape drive so that it can read/write it. On both Linux and Solaris, it is possible to open the drive with O_NONBLOCK and get a descriptor that can be used for ioctl() calls and providing there is a tape in the drive, it can be used for read() and write(). On FreeBSD, if there is no tape in the drive, the OS always immediately returns errno=ENXIO "Device not configured". This means that on FreeBSD, if there is no tape in the drive, that drive is totally unusable by Bacula. Another developer, who actually does most of the tape writing routines had two suggestions: 1. Modify Bacula and system dependent code that opens the control device to see if a tape drive is really there or not, and then rewrite the tape driver code to deal with the fact that if you cannot open a device, it may really be there, and you should continue trying to open it between asking the user to mount it. This is clearly possible. 2. Consider implementing something in FreeBSD as exists on at least Linux and Solaris -- i.e. a means to open the drive and get a valid file descriptor. If you read/write/rewind/... a drive opened and there is no tape, it should either return EIO or better ENOMEDIUM. Comments? -- Dan Langille : http://www.langille.org/ BSDCan - The Technical BSD Conference - http://www.bsdcan.org/help
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