On Wed, 19 Jan 2005 14:31:41 -0600, Jack Malone
How long does it take if you dd 1GB of /dev/zero to the tape (Be sure to adjust your block sizes)?
doing dd if=/dev/zero of=dev/st0 bs=128k i get a segmentation fault, so I can not answer that at this time.
Overall, the $100 (or less) you spend to put in a backup staging disk will more than pay for itself by eliminating wear and tear on your DLT drive.
FYI: This concept is also called a D2D2T (Disk to Disk to Tape) backup strategy, or a mezzanine backup strategy. The more sophisticated versions keep several recent backups on disk and restores from those recent backups come in directly from disk.
dd is one of the truly basic linux/unix commands. Basically anybody doing sysadm should get familiar with it. Unfortunately it has a rather unique syntax.
Thanks greg for the info. Would you suggest any other software to use for the d2d backup part of the scheme then bru. I have not bought bru just checking out the demo version is all right now. I have a cd coming in the mail ca, there rep has been calling left an right since I downloaded a windows version hehehehe. I'm not stuck on bru just trying it out since it had a demo to try.
I don't know what bru cost, but we use Data Protector from HP for our backups. It is neither cheap, nor outrageously expensive (~$1,000 to to get started, but adding networked computers to the backups set is free.) Unfortunately it requires at least one Windows box to admin the backup process.
I just need a good reliable backup scheme to use. I already have a spare 120 gig ide drive to use in the main system, an will drop i a spare in the testbench machine for testing tomorrow. I do like the ideal of the d2d2t scheme. Just hard to convince my boss of new ways of doing things at times. he is old an close to retiring. again thanks for your info an help.
All the commercial backup providers are moving to d2d2t methodologies. The middle 'd' is one of the core targets for some of HP and EMC's latest offerings. ie. Large arrays of SATA drives. Often, many TBs. IBM's Tivoli Storage Manager has supported d2d2t for several years. So you need to explain you are going upscale!!!
I have played with a 1 gig tar file an dd with setting bs=64, then bs=128k an still took 30 minutes to put it on the tape. It might be the old 3ware raid card I have in the system that is causing the slowdown, I using raid level 0 on this test machine.
well back to some more reading an testing
Try testing a raw disk to tape copy. dd if=/dev/hdc1 of=/dev/st0 bs=128k count=8000 (1GB = 128k * 8000 right?) If that is faster, then it is your filesystem that is not keeping up. If so, XFS is very good (fast) at handling large files and I recommend it for the staging disk.
jack
Greg -- Greg Freemyer