Re: Database Backup Schedules

> Clem Akins writes: > > Now that we have a clue, here's the real deal... > > We got a big digital linear tape (DLT) drive that holds 20GB, and we > > do a level 0 every day. There are several things to beware of, though: > > Informix won't support > > tape-drive level compression > > Joe Matuscak <matuscak@rohrer.com> writes: > Could you explain this a bit? Im under the impression that (in the case > of a TZ87 on Ultrix) that if you write stuff to /dev/rmt0h (for example) > the driver kicks in the compression automatically, the application isnt > really aware of whats going out to the tape. > [...sig deleted...] > > John Vemo writes: > This is something that I have never been able to understand. If your tape > drive supports H/W compression, through a seperate device access (i.e. tx0 > vs. tx0c), then why in the hell should Informix care?? This is completely > outside of Informix, all ontape or OnArchive does is pump data to a device. > If this device can, without addition calls, compress/uncompress the data as > it writes and reads from the tape, who cares?? > > OnArchive now supports compression, though its S/W compression being done by > OnArchive. This is going to slow down your archive times, since additional > cycles are now required to perform the compression. On the otherhand, drive > compression, is done at the tape drive device, and actually speeds up > archive times. > > So, go figure........ Both of you are correct. I, too, wonder what business is it of Informix's what my device does as long as it will return a valid bit stream? My archive strategy is predicated on my ability to manipulate my archives, as I write to disk, compress it, then ftp it to a VMS platform! BUT Informix still doesn't support it. If I call tech support and ask them for help with my archives they ask FIRST THING if I am using hardware compression, and if I answer "yes" then the show's over. We have talked to them a couple of times, and the problem has never been my manipulation of the archive (ftp, compress, and gzip have always put things back exactly the way they were) but I had to lie to them about what I was doing to get them to go on to the second question. (Tech support, BTW, has been mostly helpful and able to fix my problems. I've been reasonably happy, except for this major 129-row update limitation on the Alpha platform.) Your complaints and arguments are all valid, and you may direct them to Informix. I don't have any better answer, just the experience trying to get one from Informix. The purpose of my post was to share that experience with the group, so that you could save yourself some hassle with the tech support people. > > more than 1 archive per tape > > (of course that doesn't mean you can't do it...) > > There are bugs on the DEC Alpha & 7.1 when restoring from >1 tape > > Clem, could you shine a little light on your restore problem? Are you using > ontape or OnArchive?? Actually, we have no restore problem. Another user posted a problem with restoring from multiple tapes on the DEC Alpha, and I can't find his post. My sysadmin dude has some bizarre way to trigger the archive, and I think it uses ontape. I need to check with him and figure it out for myself. He talked with tech support the other day trying to figure out why we couldn't restore, and they told him that he had to be using a rewind tape device. (He had been using a norewind device, and putting more than one archive per tape.) Informix doesn't support that, either. Only one archive per tape. So now he uses a rewind device, and has a separate script which manipulates the tape to the desired position each time. :( It works, though, and he has tested it well. OnArchive and ontape check a little more closely than the older 5.x archive tools, and will be harder to fool. Complaints about this should (again) be directed to /dev/null@informix.com, or whoever it is there that logs these tirades. > [...sig, other topics deleted...] Your partner in archival crime, __________________________________________________________________ | Clem Akins Standard Disclaimers Apply | |Reynolds Metals Co, Alloys Plant "Climb High, Cave Deep!" | | Muscle Shoals, Alabama USA cwakins@leia.alloys.rmc.com | |________________________________________________________________|