nickerso@bdofed.UUCP (b) (06/29/89)
Hello World! I would like to thank all of those who responded to the request for help with the 9track tapes. We seem to have ironed out most of the problems. A quick summary of the responses follows: 1) Block size: Most of the responses suggested checking the block size. I did. The backup program was using the default cpio block size (512)! I ran some tests and found that 32k was the best (although 64k was about the same). AT&T does recommend 32k for the 9track. If anyone else is using the sysadm menus for backup, the changes could be added to /etc/savecpio. 2) Raw Device: Make sure you are using raw i/o rather than blocked. We were so there was no problem there. 3) Network: There will be a slowdown due to the bandwidth of RFS TCP/IP being less than the SCSI bus. We had expected this but we also knew that using the 9track tape should be as fast or faster than cartridge, even with the network. The performance improvements we have seen so far seem to be much more acceptable. We will know for sure after the backups are run this weekend. 4) Streaming Mode: One of the drives that AT&T OEM's is an HP 7980 that needs to have a bit set inorder to be in streaming mode. However, our drive is a Perkin-Elmer model (apparantly AT&T OEM's drives from 3 manufacturers according to one of the responses). I'm not sure if it has this bit but things seem to be smooth now so I'm assuming (we all know what that does :-) that if it does have it then it is set properly. I ran some tests and found that with the proper block size, writing to the tape (still across the ethernet) took about 1/4 to 1/3 of the time and the tape was not stopping and starting nearly as much (more writing took place on each pass!). I also discovered that the backup programs were backing up our news spool directory! We have it on one disk on our 700 machine (as it has the most space available) and have it mounted on the 622 via RFS. I had to fiddle with the /etc/savecpio script again to make sure that the dirlist variable doesn't contain the news directory (using fgrep -v to remove anything with /usr5 in its path since /usr5 contains all the news). If you want to do this yourself, keep in mind that there are two places where the changes have to be made, once for complete backups and once for incrementals. Thanks to the respondents (so far!): Steve Friedl (3B2-kind-of-guy) Paul Novorolsky Steve Paddock Robert Wilhite Micheal East Arthur Gentry and to all those whose replies may be on the way! Thanks Bill