pda@litp.UUCP (Pierre DAVID) (05/05/89)
Hello HP gurus ! I have used the "tcio(1)" command to drive an HP9144 from a 9000/319 (HP-UX 6.21). It is a clear improvement as far as speed is concerned compared to direct access to the drive. However, I have some difficulties to fully understand some of the behavior of this nice utility. - from the documentation, I understand that "-S <n>" specifies the size of memory allocated by "tcio" for its use and is without relation with the physical encoding on the tape. However, I have noticed tapes written with -S 8 that could not be read again without this option. - I have a similar problem with the "-Z" option. From the documentation I understand that this option allows a binary copy. So, for example, a tape written directly (by "tar(1)", for example) can be restored using "tcio ... -Z ... | tar ...". My attempts have been stopped by a "tcio" hang, even "kill -9" doesn't work. Generally speaking, I find that the man page is not very informative about physical operations and formats. Even more generally speaking, this remark applies to all HP-UX documentation which lacks precise technical information about devices, drivers... I find that, besides this point, the documentation is truly remarquable. Pierre DAVID pda@litp.univ-p6-7.fr
maddog@cbnews.ATT.COM (john.j.tupper) (05/09/89)
In article <2105@litp.UUCP> pda@litp.UUCP (Pierre DAVID) writes: >- from the documentation, I understand that "-S <n>" specifies > the size of memory allocated by "tcio" for its use and is without > relation with the physical encoding on the tape. However, I have > noticed tapes written with -S 8 that could not be read again > without this option. > >- I have a similar problem with the "-Z" option. From the documentation > I understand that this option allows a binary copy. So, for example, > a tape written directly (by "tar(1)", for example) can be restored > using "tcio ... -Z ... | tar ...". My attempts have been stopped by > a "tcio" hang, even "kill -9" doesn't work. The -S option only affects the amount of data transferred across the hpib in a single write, the data is stored on thap the same regardless of what -S size you use (well, almost). I can write/read tapes with different -S sizes, perhaps you have a bad tape. I have found that if I don't use the -e switch when writing tapes, I can have trouble reading them back (-e write an end of tape mark after your data). Seems especially true when used with cpio (you get extra garbage from the end of the tape and cpio chokes). It sounds like what you want is "tcio -oZVeS 8 /dev/???". Z - don't waste the first and last block for tcio overhead (you may get in trouble if your data won't fit on a single tape. I've never tried it). V - don't do a verification pass. The 9144 doesn't need it as it does a read while write. e - write a tape mark at the end of the data. S 8 - block size. You may also want to check out /usr/include/sys/cs80.h for some undocumented ioctl calls to control the tape (look at the end of the file). ---------------------------------------------------------------------- sdlfkj asdlkfowei dfs My real signature is illegible too
rjn@hpfcdc.HP.COM (Bob Niland) (05/09/89)
re: "I have used the "tcio(1)" command to drive an HP9144 from a 9000/319..." > - from the documentation, I understand that "-S <n>" specifies > the size of memory allocated by "tcio" for its use and is without > relation with the physical encoding on the tape. It implicitly specifies the maximum I/O request sent across HP-IB. Keeping it below the buffer size in the tape drive (12K or so) prevents the bus from being temporarily hung up waiting for data to make it to the tape media. > ... However, I have > noticed tapes written with -S 8 that could not be read again > without this option. The use of "S" with any value should have no effect on the data written to the tape. > - I have a similar problem with the "-Z" option. From the documentation > I understand that this option allows a binary copy. Not exactly. The default operation of tcio is to write an EOF (zero-length block as I recall) at the beginning of the tape and at /dev/rct close. This prevents accidental push-button copying of the tape to a 7908, 791x or 7942/46 disk drive. If you write with "Z" but don't specify it upon read, tcio will probably skip the first 1K [data] block, presuming that it is a ZLR. Regards, Hewlett-Packard Bob Niland rjn%hpfcrjn@hplabs.HP.COM 3404 East Harmony Road [hplabs|hpu...!hpfcse]!rjn Ft Collins CO 80525-9599
accu@hpuepta.UUCP (Accugraph Corp) (01/12/90)
The HP-UX 6.2 & 6.5 tcio(1) manual entries refer to read-while-write hardware capabilities to be described in the DEPENDENCIES section (for the -V option). However, there is no reference to this feature in that section. The 7.0 manuals do state that this feature is supported for: 7942, 7946, 7941CT, 9144A and 35401. Question: does tcio(1) support this capability in 6.2 and 6.5 (i.e. is the manual page incorrect or was something added to tcio(1) in 7.0)? Philip Webster hplabs!hpuepta!attila!pw P.S. I discovered a convenient way to block until a tape is loaded especially nice for our 35401 in seq. mode for producing our software. #! /bin/csh set src_loaded = 0 while ( $src_loaded == 0 ) sleep 30 tcio -i -S 8 /dev/update.src |& dd bs=1k count=1 >& /dev/null if ( $status == 0 ) then src_loaded = 1 endif end
wayne@dsndata.uucp (Wayne Schlitt) (01/15/90)
In article <32870010@hpuepta.UUCP> accu@hpuepta.UUCP (Accugraph Corp) writes: > > Question: does tcio(1) support this capability in 6.2 and 6.5 (i.e. is the > manual page incorrect or was something added to tcio(1) in 7.0)? > > to the best of my knowledge, yes, 6.2 and 6.5 do support the -V option. we were able to cut our backup time using a 9144 by about 30% by using "tcio -V -S 8". it still isnt blazingly fast, but every little bit helps. -wayne
kev@hpcpbla.HP.COM (Kevin Jones) (01/15/90)
The 9144A, 35401, 7914CT, 7946 drives all have read-while-write capability in hardware. Data written by a write head is immediatly read back by a read head. Verification is thus achieved "on the fly" making a verify pass redundant. Hence the "-V" option in tcio to inhibit the verify pass. The aforementioned drives will perform read-while-write irrespective of the OS revision. If an error is detected in the written data then these drives will perform retries. If the retries fail then the block being written will be re-mapped and written to a spare block on tape. Read-while-write, retries and sparing are all performed by the drives themselves. The OS (whatever its revision) has no involvement in these processes. The 9145 drive also does its own read-while-write, retries and sparing. I'm not sure what the 9142 drive does. Note: 7914P (disk with push-button-backup) tape units do not posess read while write ability. ----------------------------------------------------------------- Kevin Jones. | Hewlett Packard Ltd, | Computer Peripherals Bristol, kev%hpcpbla@hplb.hpl.hp.com | Filton Road, | Stoke Gifford, Tel: 011 44 272 799910 (ext 22351) | Bristol. BS12 6QZ. | ENGLAND. -----------------------------------------------------------------