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C1554C write hiccups

Ronald Richter
Occasional Visitor

C1554C write hiccups

We are using QNX (a realtime UNIX) in our laser radar systems and have had good success with HP DAT drives to record data. We are now using DDS3 DAT drives. While buffering data to the drive we notice that we lose data while the drive starts up and then randomly for 10 or so seconds every 5 or 6 minutes. Any ideas on what the drive is doing? or how to avoid?

using Adaptec 2930U SCSI card
Fsys.aha8scsi driver which creates /dev/tp0 using standard "C" open, write, read
3 REPLIES

Re: C1554C write hiccups

Are you going directly to the drive as apposed to a file?
Don't fix what ain't broke!
Jan Klier
Respected Contributor

Re: C1554C write hiccups

Can you be more specific about what 'loosing data' means?

Does the data stream stall? Do you get error codes while attempting to read/write? Are the data returned corrupted?
Ronald Richter
Occasional Visitor

Re: C1554C write hiccups

No error messages seen and no corrupted data. It has something to do with the buffering/start / stop or some sort of a drive reset?? I am simply blocking the data into 65K chunks and using a write. I go back and read and find the missing gaps by checking the time I recorded on each record. I have set the tape drive to immediate mode, infinite flush and am now checking to see if that helps. I changed the DIP switch on the bottom of the drive from the default all on, switch 3 off to switches 3,6,8 on.