Backups
Question: can you take a level-0 backup on Monday and a level-1 each following night, so that restoring Friday needs only Monday's L0 plus Friday's L1? Answer from several respondents: yes — a level-1 captures everything changed since the last level-0, so only those two archives are needed. Caveats noted: later-week L1s take longer/are larger as more has changed, and the backup must still scan all pages so elapsed time may not drop much. Jonathan Leffler also outlined mixing L1/L2 (e.g. L0 Mon, L2 Tue, L1 Wed, L2 Thu/Fri) to shorten nightly runs at the cost of more tapes in the restore.
Auto-generated by DrWatson from the posts below — may be imperfect; read the full thread.
Say on a Monday night we do a L0 backup, is it possible to do L1 backup for each day in the remainder of the week, meaning that if we had to restore Friday's database we would only need to run Monday's L0 and Fridays L1? Thanks in advance
You are correct. As the L1 is keeping a copy off all changed data since the last L0. -----Original Message----- From: NIGEL FORBES [mailto:forbes_mail@btinternet.com] Sent: Wednesday, May 12, 2004 7:51 AM To: ids@iiug.org Subject: Backups [2953] Say on a Monday night we do a L0 backup, is it possible to do L1 backup for each day in the remainder of the week, meaning that if we had to restore Friday's database we would only need to run Monday's L0 and Fridays L1? Thanks in advance
Hi, yes. Of course, Fridays level-1 backup will take more backup time than Tuesdays level-1 backup (as on Friday there will be more changes since Monday than there are on Tuesdays) ... Regards, Martin -- Martin Fuerderer IBM Informix Development Munich Data Management Solutions "NIGEL FORBES" <forbes_mail@btinternet.com> Sent by: forum.subscriber@iiug.org 12.05.2004 13:51 To ids@iiug.org cc Subject Backups [2953] Say on a Monday night we do a L0 backup, is it possible to do L1 backup for each day in the remainder of the week, meaning that if we had to restore Friday's database we would only need to run Monday's L0 and Fridays L1? Thanks in advance
Is that really true? Isn't Informix going to have to read each page of the database to determine its age and thus whether or not it belongs in the Level 1 archive? Yes, there will be less writing to tape, but if that's not the bottleneck, I'd think it would take just as long. --John Bejarano. --- "Martin Fuer...." <MARTINFU@de.ibm.com> wrote: > Hi, > > yes. > > Of course, Fridays level-1 backup will take more > backup time > than Tuesdays level-1 backup (as on Friday there > will be more > changes since Monday than there are on Tuesdays) ... > > Regards, > Martin > -- > Martin Fuerderer > IBM Informix Development Munich > Data Management Solutions > > > > > "NIGEL FORBES" <forbes_mail@btinternet.com> > Sent by: forum.subscriber@iiug.org > 12.05.2004 13:51 > > To > ids@iiug.org > cc > > Subject > Backups [2953] > > > > > > > Say on a Monday night we do a L0 backup, is it > possible to do L1 backup > for each day in the remainder of the week, meaning > that if we had to > restore Friday's database we would only need to run > Monday's L0 and > Fridays L1? > > Thanks in advance > > > > >
So, an alternative, more complex backup system would be: Monday: L0 Tuesday: L2 Wednesday: L1 Thursday: L2 Friday: L2 Recovering on Monday uses just the L0; on Tuesday, the L0 and L2; on Wednesday, the L0 and L1; on Thursday or Friday, the L0, L1 and L2. However, since you need to recover all the changes since Monday (the L0), the total volume of the backups will be roughly equivalent. OTOH, the L2's will be quicker to take because less has changed since the preceeding L1 or L0 backup. Tuesday's backup could be L1 without directly affecting anything except the labelling. Ring the changes to suit yourself. -- Jonathan Leffler (jleffler@us.ibm.com) STSM, Informix Database Engineering, IBM Data Management 4100 Bohannon Drive, Menlo Park, CA 94025 Tel: +1 650-926-6921 Tie-Line: 630-6921 "I don't suffer from insanity; I enjoy every minute of it!" forum.subscriber@iiug.org wrote on 05/12/2004 07:33:23 AM: > Hi, > > yes. > > Of course, Fridays level-1 backup will take more backup time > than Tuesdays level-1 backup (as on Friday there will be more > changes since Monday than there are on Tuesdays) ... > > Regards, > Martin > -- > Martin Fuerderer > IBM Informix Development Munich > Data Management Solutions > > > > > "NIGEL FORBES" <forbes_mail@btinternet.com> > Sent by: forum.subscriber@iiug.org > 12.05.2004 13:51 > > To > ids@iiug.org > cc > > Subject > Backups [2953] > > > > > > > Say on a Monday night we do a L0 backup, is it possible to do L1 backup > for each day in the remainder of the week, meaning that if we had to > restore Friday's database we would only need to run Monday's L0 and > Fridays L1? > > Thanks in advance > > > > >
Good point - the time taken to do the back will depend on the size of the instance, the amount of disk space that changes between L0 backups, the relative speeds of the disks and the backup device (which can be extremely fast if it is a NAS/SAN system), and, no doubt, on the colour of the DBSA's shirt the day before the backup starts. OK - maybe not the shirt colour, but there are going to be other factors too. Martin's point, though, that the amount to be backed up will be smaller is valid. -- Jonathan Leffler (jleffler@us.ibm.com) STSM, Informix Database Engineering, IBM Data Management 4100 Bohannon Drive, Menlo Park, CA 94025 Tel: +1 650-926-6921 Tie-Line: 630-6921 "I don't suffer from insanity; I enjoy every minute of it!" forum.subscriber@iiug.org wrote on 05/12/2004 01:13:31 PM: > Is that really true? Isn't Informix going to have to > read each page of the database to determine its age > and thus whether or not it belongs in the Level 1 > archive? Yes, there will be less writing to tape, but > if that's not the bottleneck, I'd think it would take > just as long. > > --John Bejarano. > > --- "Martin Fuer...." <MARTINFU@de.ibm.com> wrote: > > Hi, > > > > yes. > > > > Of course, Fridays level-1 backup will take more > > backup time > > than Tuesdays level-1 backup (as on Friday there > > will be more > > changes since Monday than there are on Tuesdays) ... > > > > Regards, > > Martin > > -- > > Martin Fuerderer > > IBM Informix Development Munich > > Data Management Solutions > > > > > > > > > > "NIGEL FORBES" <forbes_mail@btinternet.com> > > Sent by: forum.subscriber@iiug.org > > 12.05.2004 13:51 > > > > To > > ids@iiug.org > > cc > > > > Subject > > Backups [2953] > > > > > > > > > > > > > > Say on a Monday night we do a L0 backup, is it > > possible to do L1 backup > > for each day in the remainder of the week, meaning > > that if we had to > > restore Friday's database we would only need to run > > Monday's L0 and > > Fridays L1? > > > > Thanks in advance > > > > > > > > > > > >
John, A lot of people, including myself, think of backup duration being "it started at hh:mm:ss and finished at hh:mm:ss". We also believe that the purpose of a database is to have records added/modified/deleted on a daily basis. You are technically correct. The process that performs the backup will have to read page headers to determine if they need to be backed up. Given that the system activity remains constant, If no changes have beeen made since Monday's archive, the archive taken Friday will be approximately the same. However, when a page needs to be backed up, the process "slows down" to write that information to whatever device. Because of the assumption that more data will be modified/added from Monday's archive until Friday's archive, an increase in the amount of time it takes to perform is expected. Take care. Clifton John Bejarano <jbejarano@sbcglobal.net> wrote: Is that really true? Isn't Informix going to have to read each page of the database to determine its age and thus whether or not it belongs in the Level 1 archive? Yes, there will be less writing to tape, but if that's not the bottleneck, I'd think it would take just as long. --John Bejarano. --- "Martin Fuer...." wrote: > Hi, > > yes. > > Of course, Fridays level-1 backup will take more > backup time > than Tuesdays level-1 backup (as on Friday there > will be more > changes since Monday than there are on Tuesdays) ... > > Regards, > Martin > -- > Martin Fuerderer > IBM Informix Development Munich > Data Management Solutions > > > > > "NIGEL FORBES" > Sent by: forum.subscriber@iiug.org > 12.05.2004 13:51 > > To > ids@iiug.org > cc > > Subject > Backups [2953] > > > > > > > Say on a Monday night we do a L0 backup, is it > possible to do L1 backup > for each day in the remainder of the week, meaning > that if we had to > restore Friday's database we would only need to run > Monday's L0 and > Fridays L1? > > Thanks in advance > > > > >