Date: Thu, 03 Sep 1998 21:57:35 -0500 From: David Kelly <dkelly@hiwaay.net> To: Frank Terhaar-Yonkers <fty@cisco.com> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: 8mm tape block size max - changed? Message-ID: <199809040257.VAA17656@nospam.hiwaay.net> In-Reply-To: Message from Frank Terhaar-Yonkers <fty@cisco.com> of "Wed, 02 Sep 1998 21:19:42 EDT." <199809030119.VAA25476@claret.cisco.com>
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Frank Terhaar-Yonkers writes:
>
> Folks -
>
> I recently upgraded from 2.0.x where I routinely used a block size of
> 128b with tar and dump. Using 2.1.7 I get: st0: 64512-byte record too big
> when I try to read the old tapes.
>
> Now I have all these old tapes I can't read. Am I missing something?
So you used "tar -cvb 128 files" to write a tar tape?
Would suggest you try using tcopy to determine what blocksize is being
used but I just tried it myself and it didn't work right at all.
Multiple tape blocks were read to serve one read(). If this is
happening to you then that may be the key to the puzzle:
The following tape was written "tar -cvb 20", tcopy clearly reports an
incorrect block size and would mangle this tape if I were to actually
copy it:
n4hhe: {541} tcopy
file 0: block size 65536: records 0 to 7
file 0: block size 43008: record 7
file 0: eof after 8 records: 501760 bytes
eot
total length: 501760 bytes
n4hhe: {542}
The above is *not* the way I'm used to seeing tcopy work. Am
dissapointed. Recently ported FreeBSD's tcopy to SGI Irix 6.3 and had
the same problem if a non-variable blocksize device was used (ie:
/dev/rmt/tps1d6nrv worked, /dev/rmt/tps1d6nr would supply multiple
blocks to fill the read() request).
So maybe I'm just using the wrong FreeBSD tape device?
dmesg
says:
(ahc0:6:0): "ARCHIVE ANCDA 2750 28077 -003" type 1 removable SCSI 2
st0(ahc0:6:0): Sequential-Access density code 0x10, 512-byte blocks, write-enabled
To my knowlege FreeBSD has never been able to write blocks larger than
64k to tape devices but would hide large writes with multiple smaller
writes. So with any luck if you were writing 128 * 512 bytes then you
should be OK.
THe 64512 number you quote has everyone confused.
--
David Kelly N4HHE, dkelly@nospam.hiwaay.net
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