I think this bug is actually in glibc or something similar, rather than tar. Prior to upgrading to RedHat 5.0, we saw nice speedy transfers at 15-20 MB/min, afterward they have slowed to about 3 MB/min. The context is this: a SCSI 4-mm tape drive is located on an Alpha OSF 4.0E host. From that host we use ssh or rsh (doesn't matter which for this problem) to connect to a Linux host, which then runs tar with output to a filespec of the form osfhost:/dev/tape. The network is a 10 Mbs ethernet (mix of thinwire and CAT-5 UTP). The Linux hosts have a variety of NICs: tlan, ewrk3, eepro100, so it does not seem to be a driver problem. The same OSF host can back up another OSF host or an AIX host on the same local network at 15-20 MB/min, which is close to the limit set by the tape speed. We do not see any abnormal network-related messages in the logs on either host during the transfer. File transfers via NFS or ftp go at the normal high rate, limited only by network bandwidth. The slowness only shows up when using tar.
we never were able to duplicate this. If you are still having problems, or the problem was not solved in 6.1, please reopen the bug.