From mboxrd@z Thu Jan 1 00:00:00 1970 From: ael Subject: Re: st.c block limits Date: Thu, 01 Aug 2002 12:57:02 +0100 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <3D49220E.3030003@ntlworld.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Id: linux-scsi@vger.kernel.org To: Kai Makisara Cc: linux-scsi@vger.kernel.org Kai Makisara wrote: > On Tue, 30 Jul 2002, ael wrote: > > >>I have a scsi tape drive:- >> >>Host: scsi0 Channel: 00 Id: 00 Lun: 00 >> Vendor: AIWA Model: TD-20001 Rev: 0159 >> Type: Sequential-Access ANSI SCSI revision: 02 >> >>It has worked perfectly for several years, but from kernel 2.4.10 st.c >>started to report a 24-bit block limit: st0: Block limits 1 - 16777215 >>bytes. I am now on stock 2.4.18 with static char *verstr = "20020205". >> >>The above drive is a NS-20 drive with default block size of 512 and 20G >>blocks: so a range of 25 bits for the block number is needed. >> > > The block limits tell the block size limits the drive reports, not limits > to the amount of data. The driver writes data until the drive tells that > there is no space. I.e., the driver does not limit the amount of data > written to the tape. No changes affecting this behaviour has been made for > a very long time. > > >>So when I attempt to write to the tape beyond block 2^24, >>I get an error like: >> >># tar -cf /dev/ntape blah_home.tar.bz2; mt tell >>tar: /dev/ntape: Wrote only 0 of 10240 bytes >>tar: Error is not recoverable: exiting now >>At block 17832312. >> > > Looks like you are at end of tape. I think the 20 GB capacity is > compressed and not real. This means that the actual amount of data you can > write on the tape depends on the compressibility of data. 17.8 GB is > actually not too bad in this case. > > Kai Following up my previous reply where I noted that I had only written 8.8Gb to a tape with uncompressed capacity of 10Gb, it then seems that the tape firmware is reporting a maximum drive capacity of ~ 16GB. And perhaps a real tape limit of 17832312 /2 = 8.9GB which is supposedly on a 10GB tape : Imation NS-20, specified as 10GB uncompressed. Should I ask Imation for replacements :-) ? ael