*- On 3 Feb, Jason Gunthorpe wrote about "Re: no improvement using buffer with tar?" > > On Wed, 3 Feb 1999 [EMAIL PROTECTED] wrote: > >> I guess I was a little disappointed with respect to its claims and its >> actual performance. I would like to speed up my backup, as it is now a >> backup of my system containing about 5.5Gigs takes almost 5.5hrs. That >> is only about 275k/s transfer rate which is way below the capabilities >> of the drive. Which leads me to believe there can be improvements on the >> software side of my backup. > > Listen to the tape while it is running, it should basically emit a nice > constant sound. If it doesn't and you hear it 'back up' then that is why
Yep, it does that. > things are so slow for you. It may well be that you bought a tape drive > that requires a higher data rate than your PCee can sustain, this is what > buffer is supposed to help with. Make a -really- big buffer (like 10-50 > meg) and set the low/high marks at the far end so that it generates a big > wack meg of data and then starts feeding the tape.. Now if your disks and Buffer would only accept a 20 meg maximum buffer. How can I increase the shared memory so that it will use more, I have 96 meg of ram? The backups are done at night so nothing is active so it should be able to swap other things out. I know nothing about shared memory. > your CPU (compression) can mostly keep up with the tape then you will be > fine with this, but if the tape vastly outmatches your systems performance > (ie it can stream 2meg/sec or something crazy like that) then you will > see little or no speed gain and possibly even a loss. > I have a P233 and the specs on the scsi-2 tape drive are: Transfer Rate (Kbytes/sec) 600/450/300 Tape Speed Read/Write (ips) 75/51/33 Search/Rewind (ips) 90 Backup Rate, Sustained Native (Mbytes/min, max) 30 Compressed (Mbytes/min, max) 60 Thanks for your input. I have done some trials today and with what I could use for the buffer size it did a little better. It looks like the bottleneck is when tar gets to large files, aka CPU. Thanks, -- Brian
