Trouble reading Informix backup on DLT device.

Trouble reading ontape backup on DLT tape ! Compressed or uncompressed backup om DLT-tape ? System: SUN Sparccenter 3000, Solaris 2.5.1, Informix 7.20.UC2 We take an Informix backup via crontab command every night: Command in root's crontab: 00 05 * * 1-5 su - informix -c "ontape -s -L 0" After first delivery of new DLT-4000 tape device with supplied 5 tapes (DLT IV) everything was OK. Writing backups and reading tapes worked OK. When we bought more tapes (another 10 now DLT IV with blue SUN logotype) from SUN Express and put them into circulation everything seemed perfectly until first attempt to read the backup tape. It was not readable!! The system did not seem to like to read the tapes (error in the beginning of the tape). After some investigating by service engineer it seems that the system was configured (Informix onconfig TAPEDEV) for compressed backup and the new tapes could not handle the format. It seemed that writing backup worked OK but reading worked not OK. ONCONFIG # System Archive Tape Device TAPEDEV /dev/rmt/2c # Tape device path TAPEBLK 126 # Tape block size (Kbytes) TAPESIZE 40000000 # Maximum amount of data to put on tape (Kbytes) # Log Archive Tape Device LTAPEDEV /dev/rmt/1n # Log tape device path LTAPEBLK 126 # Log tape block size (Kbytes) LTAPESIZE 8000000 # Max amount of data to put on log tape (Kbytes) After correcting to uncompressed format. TAPEDEV /dev/rmt/2 # Tape device pathEverything seema OK, both writing and reading (at least the labels of the tape with ontape-commands) Questions Is there two (or more) "tape qualities"? (All seems to bee DLT IV tapes.) Is there a special problem with "parameters etc." for using compressed or uncompressed backups on DLT 4000 ? We have plenty of space on DLT tape is uncompressed format the best ? Any suggestions or tips regarding this matter i most welcome. /Best regard Christer Widell cwidell@hotell.itz.se