checking ontape -s -L

Hello, Working on a NT server (Alpha processor, BaaN application) and using ontape -s -L 0 (informix 7.23TC1) , I want to check the following how much space is left on the tape or how many bytes are written to the tape. The tape is a DLT IV tape and can contain 20 GB uncomp. or 40 GB compressed. Since our db is 11*2GB chunks I want to be sure the tape is big enough. what is the size of the tape in the onconfig file, 20 GB, 40 GB or between 20 and 40 GB ? how to verify the backup ? Thanks, Daniel Willems

Daniel Willems wrote: > > Hello, > Working on a NT server (Alpha processor, BaaN application) and using > ontape -s -L 0 (informix 7.23TC1) , I want to check the following > how much space is left on the tape or how many bytes are written to the > tape. The tape is a DLT IV tape and can contain 20 GB uncomp. or 40 GB > compressed. Since our db is 11*2GB chunks I want to be sure the tape is big > enough. That depends on your data. The compressed capacity reported for tape drives assumes best compression which is typically only acquired for databases that are mostly text. If your database is mostly binary data you may one get 30 - 35GB on a tape. The best compression may change over time. Just this weekend I had news server archives fail on two servers because the data no longer compresses to the same degree, probably more Chinese and Japanese stories filed lately. I had to reduce the tape capacity in ONCONFIG and restart the archives. > what is the size of the tape in the onconfig file, 20 GB, 40 GB or > between 20 and 40 GB ? Start with 40 * (1024 * 1024) (you enter KB) and work your way down until it no longer fails with errno 28 (no space left on device). Or start with 30 * (1024 * 1024) and work your way up until it fails. When figuring capacity needs discount tempdb spaces they are never archived and only count the used pages of your server, free space is also never archived. In addition, only level zero archives will backup every page unless you have an unusually busy system. > how to verify the backup ? Vers 7.30 comes with archecker which can verify that an archive is complete and consistent. It is available for special needs for older versions from tech support. Art S. Kagel