On Tue, 18 Jan 2005 13:41:29 -0600, Jack Malone wrote:
At 01:25 PM 1/18/2005, Greg Freemyer wrote:
That's pretty slow. It is bad for your DLT drive to run that slow, so you really do need to make the process faster. (i.e. The shoe-shining noises you are hearing are adding lots of wear and tear to the tape drive.)
How long does it take if you backup your 1GB to /dev/null?
How long does it take if you dd 1GB of /dev/zero to the tape (Be sure to adjust your block sizes)?
Typically a slow backup is caused by traversing the filesystem, not the tape system.
Assuming that it is bru (ie. the filesystem) that is slow, with only 11 GB you will be better off to do your BRU backup do a dedicated xfs filesystem on a dedicated drive. (ie. /dev/hdc1).
Then just dd the backup file to tape. That way the tape / filesystem speed issues will not degrade each other.
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.
Hey Greg, thanks for replying back. I also did this same test with tar an it took the same amount of time. Now the 1 gig stuff I backed up was not the same stuff that would be backed up when I put the system into production. I am doing this on my test bench machine here my office before I put it in the actual server. I do have a spare hd in the server to help with the d2d2t setup already. I used to have a dat drive in a windows machine that backed up the server samba share at night an it would do this 11 gigs in 2 hours time, ( my bosses ideal to keep it in the workstation). Back in dec that dat tape drive went bad after 5 years of use. I also backup the samba share to my workstations to a hard drive for that purpurse only an keep a few weeks of backups that way right now. I convince boss to put the new tape drive in linux server if i can get it working right.
Ok so you say to dd the backup file to tape, I'm assuming your meaning to us dd to archive/ copy the backup file to the tape drive. After I hear back from you I will give this a try. never used the dd command but have seen serval messages referencing it in other ways.
thanks jack
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. Anyway, assume your backup is at /mnt/backup.bru To put that to tape: dd if=/mnt/backup.bru of=/dev/st0 bs=64k if --- input file of -- output file bs -- blocksize (Pick one you like, but be consistent. I always write it on the tape label). Two other args I use a lot are 'count=xxx' and 'conv=noerror,sync'. You should be able to use bru to directly restore a tape made like above, as long as you give dd and bru the same block sizes. If for some reason bru won't restore from tapes made this way you can use dd to restore to disk, then bru to restore from the disk file. Greg -- Greg Freemyer