Summary: OnLine backup strategy

OnLine Backup Strategies: I promised to post a summary after three weeks. Here it comes, a bit shortened, of course: Quintessence: It looks like my proposals should work, because I do expect huge data. Continuous backup is considered important. Thanks to all who responded! -svb. ---------------------------------------------------------------------- Nancy Howe <nhowe@informix.com> forwarded a letter from Dave (???) > Question 1: > Before dumping I force a checkpoint, after dumping I "backup" all logs > to /dev/null (??? *shiver*) I _think_, I don't need them after > archiving at any level. Any holes in there? I want to keep my client, > even after a crash ;-) Once you have the archive, you do not need any log tapes *previous* to the archive. You do need whichever one was current at the time the archive started, and any following that one. So dumping old logs shouldn't be a problem. Of course, should that archive turn out to be bad... > Question 2: > Are there any formulas for the required number of logicals logs? Something > like F(x) = n where x = avg(io) and n = #logs? Or is it just try and > error? No formula; the only requirement is that you must have a minimum of 3 logs. (There are some strategies outlined in the 5.0 OnLine Administrator's manual, but every site is different. Do you have access to the 5.0 Admin Guide? If not, let me know if you want more general info and I can send you some excerpts. Nancy) > Question 3: > Any further suggestions? hints? remarks? questions :-) ? Seb, I was going to say, "not really, other than the strategies" and ask you if you received any good advice from other users. Hmmm, Dave quips, "Lots of insurance..." > Thank you for your opinions, tips and tricks, I'll summarize, if > wanted, in about three weeks. Hoping for a bunch of input.... Dave ---------------------------------------------------------------------- From: Dave Snyder <dave.snyder@snide.com> > Every month a full dump level 0 > every friday a dump level 1 > every night a dump level 2 after receiving the incoming uucp data. That's ok I guess, what's wrong with a level 0 every friday and a level 1 every night (unless you have HUGE quantities of data). > Question 1: > Before dumping I force a checkpoint, after dumping I "backup" all logs > to /dev/null (??? *shiver*) I _think_, I don't need them after > archiving at any level. Any holes in there? I want to keep my client, > even after a crash ;-) Nothing wrong, but if you do continuous logical log backups... you don't have to backup the logs to /dev/null and you have all the work up to the last log dump if your hard disk deceides to melt-down. > Question 2: > Are there any formulas for the required number of logicals logs? Something > like F(x) = n where x = avg(io) and n = #logs? Or is it just try and > error? The nice guys at Informix faxed me some formulas once... it was worthless. Not the formulas, what Informix Tech-support faxed was perfect and would have worked. The problem was you needed to know what every user was going to be doing to the database and when... a definite impossibility in my environment. > Question 3: > Any further suggestions? hints? remarks? questions :-) ? Just a recap... do level 0 archives on Fridays, do level 1 archives daily unless you have HUGE quantities of data. If thats the case go with your original idea. Backup you logical logs on a continous basis, you'll be glad you did. And lastly, don't tell customers that a product will solve certain problems unless you've actually tried it :-) ---------------------------------------------------------------------- From: jeff@cbis.ECE.Drexel.EDU (Jeff White) >Every month a full dump level 0 >every friday a dump level 1 >every night a dump level 2 after receiving the incoming uucp data. > >I hope that's ok so far. Depends, of course, on the data. > >Question 1: >Before dumping I force a checkpoint, after dumping I "backup" all logs >to /dev/null (??? *shiver*) I _think_, I don't need them after >archiving at any level. Any holes in there? I want to keep my client, >even after a crash ;-) That seems to be okay. At the place I am working, we are currently in semi-disagreement as to whether the logs are necessary after you do an archive. I seem to think not, and from how I read it the Informix manual seems to agree. > >Question 2: >Are there any formulas for the required number of logicals logs? Something >like F(x) = n where x = avg(io) and n = #logs? Or is it just try and >error? Informix gives their formula as logical logs:physical logs = 3:1, and logical logs + physical logs = 20% of data space. For our setup, we have 1 Gig of data, and 200Meg for logs seemed excessive, so I cut that down to somewhere between 50 and 100. I think the logical log size is fixed, so the only way to change it is to wipe out your data. Seeing as we didn't want to do it, we left it at the original setting of 750, but created 50 logs. Jeff White jeff@cbis.ece.drexel.edu ----------------------------------------------------------------------