informix and SAN snapshot

Hi all Informix experts, i would like to put the Informix DB v9.x on SAN and take snapshots daily so that in case there is data corruption, I can rollback to previous version. However, I found Informix is a bit different from Oracle and Sybase as they have backup modes but Informix doesn't have. (Correct me if I'm wrong) I did do some researches on the Internet and found a utility called onbar. Can I use this command to temporarily freeze the DB before I take a snapshot on the SAN so that the snapshot taken will have no integrity issue? If so, during the snapshoting, where will the new transactions go? Will the new transactions be temporarily stored on somewhere else? Thanks a lot in advance. Regards, vt

You can block the database using "onmode -c block" - it causes the database to enter a checkpoint and wait for you to issue the "onmode -c unblock" command to let the database proceed. This will block all transactions while you are doing the snapshot though - no caching etc and users will get error messages when they try to do anything. Jarrod Teale Fonterra NZ. ________________________________ From: informix-list-bounces@iiug.org [mailto:informix-list-bounces@iiug.org] On Behalf Of vt Sent: Tuesday, 25 November 2008 3:20 p.m. To: informix-list@iiug.org Subject: informix and SAN snapshot Hi all Informix experts, i would like to put the Informix DB v9.x on SAN and take snapshots daily so that in case there is data corruption, I can rollback to previous version. However, I found Informix is a bit different from Oracle and Sybase as they have backup modes but Informix doesn't have. (Correct me if I'm wrong) I did do some researches on the Internet and found a utility called onbar. Can I use this command to temporarily freeze the DB before I take a snapshot on the SAN so that the snapshot taken will have no integrity issue? If so, during the snapshoting, where will the new transactions go? Will the new transactions be temporarily stored on somewhere else? Thanks a lot in advance. Regards, vt

Call your SAN vendor and ask them. With Oracle and EMC you set the database into hot backup mode, perform the split mirror, then take the database out of hot backup mode. Something tells me it will be onmode -c block or onmode -c unblock as the equivalent. I tried this on my own test box, then went to Google to see if I was on the right track. You can test this on a developer instance to see how it works. I don't have a SAN handy to test on so you'll have to script on your own. Whatever SAN you use, the terminology will be something like 'split mirror' or BCV. onmode -c block onstat IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days 05:51:53 -- 39728 KbytesBlocked:ARCHIVE . . do the split mirror here . onstat onmode -c unblock IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days 05:52:52 -- 39728 Kbytes See also: =========== http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1227584103536+28353475&threadId=88210 "Look into the command: onmode -c block You run this, and it does a checkpoint and blocks any more activity to the disks. You then split off the bcv mirror. Because you did a checkpoint, the split copy will be consistient at the time of the checkpoint. To re-enable disk activity, do: onmode -c unblockI believe there is a white paper on Informix's website about this." =========== You can search Google for 'Informix BCV' or 'Informix split mirror' and get more info. -ID- vt wrote: > Hi all Informix experts, > > i would like to put the Informix DB v9.x on SAN and take snapshots daily > so that in case there is data corruption, I can rollback to previous > version. However, I found Informix is a bit different from Oracle and > Sybase as they have backup modes but Informix doesn't have. (Correct me > if I'm wrong) > > I did do some researches on the Internet and found a utility called > onbar. Can I use this command to temporarily freeze the DB before I take > a snapshot on the SAN so that the snapshot taken will have no integrity > issue? If so, during the snapshoting, where will the new transactions > go? Will the new transactions be temporarily stored on somewhere else? > Thanks a lot in advance. > > Regards, vt

Jarrod Teale wrote: > You can block the database using "onmode -c block" - it causes the > database to enter a checkpoint and wait for you to issue the "onmode -c > unblock" command to let the database proceed. This will block all > transactions while you are doing the snapshot though - no caching etc > and users will get error messages when they try to do anything. > > Jarrod Teale > Fonterra NZ. > Jarrod, Sorry I didn't see your post... we must've both posted close to the same time. I'm curious if you use Informix MVCC if this is the case, that is, are the users still blocked? I'd think if MVCC is being used that it would be like Oracle, but I'm not sure. Looks like worse case you have to create a maintenance window and get users off the system for the split. However, it will only be lengthy the first time, at least with EMC. Subsequent splits should be on the order of a few seconds. At any rate looks like you've confirmed what I was thinking is the right thing to do, how long it takes to complete is another matter. -ID-

I don't actually use it for my systems at all - I just heard a bunch of people talking about it at the Informix On Demand conference in Las Vegas earlier this month and they suggested this was the way to go. They also suggested using some of the features of MACH11 to do the same job (SDS for example) - but not an option in this case as the DB is version 9 -----Original Message----- From: informix-list-bounces@iiug.org [mailto:informix-list-bounces@iiug.org] On Behalf Of InDeep Sent: Tuesday, 25 November 2008 4:58 p.m. To: informix-list@iiug.org Subject: Re: informix and SAN snapshot Jarrod Teale wrote: > You can block the database using "onmode -c block" - it causes the > database to enter a checkpoint and wait for you to issue the "onmode > -c unblock" command to let the database proceed. This will block all > transactions while you are doing the snapshot though - no caching etc > and users will get error messages when they try to do anything. > > Jarrod Teale > Fonterra NZ. > Jarrod, Sorry I didn't see your post... we must've both posted close to the same time. I'm curious if you use Informix MVCC if this is the case, that is, are the users still blocked? I'd think if MVCC is being used that it would be like Oracle, but I'm not sure. Looks like worse case you have to create a maintenance window and get users off the system for the split. However, it will only be lengthy the first time, at least with EMC. Subsequent splits should be on the order of a few seconds. At any rate looks like you've confirmed what I was thinking is the right thing to do, how long it takes to complete is another matter. -ID- _______________________________________________ Informix-list mailing list Informix-list@iiug.org http://www.iiug.org/mailman/listinfo/informix-list DISCLAIMER: This email contains confidential information and may be legally privileged. If you are not the intended recipient or have received this email in error, please notify the sender immediately and destroy this email. You may not use, disclose or copy this email or its attachments in any way. Any opinions expressed in this email are those of the author and are not necessarily those of the Fonterra Co-operative Group. http://www.fonterra.com/

Thanks Indeep, I'm actually trying to put Informix v9.3r5 on EMC SAN. I've already contacted EMC and they said there's no such snapshot agent for Informix. However, EMC backup software called Networker does have a backup agent for Informix. The agent is an API which interacts w/ the "Onbar" utility to backup the DB to tape even though the DB is still online. It seems to me even though the backup is in progress, the DB can still accept new transactions. I'm wondering if I can apply this approach to SAN backup / snapshot. But heard from Derby, it seems that there's no way to accept new transactions when backup is in progress. Regards, "InDeep" <indeep@indeep.com> wrote in message news:492b752e$0$18357$6c36adad@news.usenetserver.com... > Call your SAN vendor and ask them. > > With Oracle and EMC you set the database into hot backup mode, perform > the split mirror, then take the database out of hot backup mode. > > Something tells me it will be onmode -c block or onmode -c unblock as the > equivalent. I tried this on my own test box, then went to Google to see > if I was on the right track. You can test this on a developer instance to > see how it works. I don't have a SAN handy to test on so you'll have to > script on your own. Whatever SAN you use, the terminology will be > something > like 'split mirror' or BCV. > > onmode -c block > onstat> > IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days > 05:51:53 -- 39728 Kbytes> Blocked:ARCHIVE > > . > . do the split mirror here > . > > onstat > onmode -c unblock> > IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days > 05:52:52 -- 39728 Kbytes > > See also: > > =========== > > http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1227584103536+28353475&threadId=88210> > "Look into the command: onmode -c block > You run this, and it does a checkpoint and blocks any more activity to the > disks. You then split off the bcv mirror. Because you did a checkpoint, > the split copy will be consistient at the time of the checkpoint. > To re-enable disk activity, do: > onmode -c unblock> I believe there is a white paper on Informix's website about this." > > =========== > > You can search Google for 'Informix BCV' or 'Informix split mirror' > and get more info. > > -ID- > > vt wrote: >> Hi all Informix experts, >> i would like to put the Informix DB v9.x on SAN and take snapshots daily >> so that in case there is data corruption, I can rollback to previous >> version. However, I found Informix is a bit different from Oracle and >> Sybase as they have backup modes but Informix doesn't have. (Correct me >> if I'm wrong) >> I did do some researches on the Internet and found a utility called >> onbar. Can I use this command to temporarily freeze the DB before I take >> a snapshot on the SAN so that the snapshot taken will have no integrity >> issue? If so, during the snapshoting, where will the new transactions go? >> Will the new transactions be temporarily stored on somewhere else? Thanks >> a lot in advance. >> Regards, vt

They have taken you down the wrong path because you used the word 'backup'. You want to use the term 'split mirror' or BCV. Follow the pseudo code I gave you. It's that simple. Once the database is blocked, start your BCV. Once the BCV is completed, unblock your database. It's not as difficult as it seems, however, EMC has made a lot of money off of their complexity. To Informix's credit it is much simpler than Oracle. -ID- vt wrote: > Thanks Indeep, > > I'm actually trying to put Informix v9.3r5 on EMC SAN. > I've already contacted EMC and they said there's no such snapshot agent for > Informix. However, EMC backup software called Networker does have a backup > agent for Informix. The agent is an API which interacts w/ the "Onbar" > utility to backup the DB to tape even though the DB is still online. It > seems to me even though the backup is in progress, the DB can still accept > new transactions. I'm wondering if I can apply this approach to SAN backup / > snapshot. But heard from Derby, it seems that there's no way to accept new > transactions when backup is in progress. > > Regards, > > > "InDeep" <indeep@indeep.com> wrote in message > news:492b752e$0$18357$6c36adad@news.usenetserver.com... >> Call your SAN vendor and ask them. >> >> With Oracle and EMC you set the database into hot backup mode, perform >> the split mirror, then take the database out of hot backup mode. >> >> Something tells me it will be onmode -c block or onmode -c unblock as the >> equivalent. I tried this on my own test box, then went to Google to see >> if I was on the right track. You can test this on a developer instance to >> see how it works. I don't have a SAN handy to test on so you'll have to >> script on your own. Whatever SAN you use, the terminology will be >> something >> like 'split mirror' or BCV. >> >> onmode -c block >> onstat>> >> IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days >> 05:51:53 -- 39728 Kbytes>> Blocked:ARCHIVE >> >> . >> . do the split mirror here >> . >> >> onstat >> onmode -c unblock>> >> IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days >> 05:52:52 -- 39728 Kbytes >> >> See also: >> >> =========== >> >> http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1227584103536+28353475&threadId=88210>> >> "Look into the command: onmode -c block >> You run this, and it does a checkpoint and blocks any more activity to the >> disks. You then split off the bcv mirror. Because you did a checkpoint, >> the split copy will be consistient at the time of the checkpoint. >> To re-enable disk activity, do: >> onmode -c unblock>> I believe there is a white paper on Informix's website about this." >> >> =========== >> >> You can search Google for 'Informix BCV' or 'Informix split mirror' >> and get more info. >> >> -ID- >> >> vt wrote: >>> Hi all Informix experts, >>> i would like to put the Informix DB v9.x on SAN and take snapshots daily >>> so that in case there is data corruption, I can rollback to previous >>> version. However, I found Informix is a bit different from Oracle and >>> Sybase as they have backup modes but Informix doesn't have. (Correct me >>> if I'm wrong) >>> I did do some researches on the Internet and found a utility called >>> onbar. Can I use this command to temporarily freeze the DB before I take >>> a snapshot on the SAN so that the snapshot taken will have no integrity >>> issue? If so, during the snapshoting, where will the new transactions go? >>> Will the new transactions be temporarily stored on somewhere else? Thanks >>> a lot in advance. >>> Regards, vt > >

On Nov 25, 7:14 am, InDeep <ind...@indeep.com> wrote: > They have taken you down the wrong path because you used the word 'backup'. > > You want to use the term 'split mirror' or BCV. > > Follow the pseudo code I gave you.  It's that simple. > > Once the database is blocked, start your BCV. > > Once the BCV is completed, unblock your database. > > It's not as difficult as it seems, however, EMC has made a lot of > money off of their complexity. > > To Informix's credit it is much simpler than Oracle. > > -ID- > > > > vt wrote: > > Thanks Indeep, > > > I'm actually trying to put Informix v9.3r5 on EMC SAN. > > I've already contacted EMC and they said there's no such snapshot agent for > > Informix. However, EMC backup software called Networker does have a backup > > agent for Informix. The agent is an API which interacts w/ the "Onbar" > > utility to backup the DB to tape even though the DB is still online. It > > seems to me even though the backup is in progress, the DB can still accept > > new transactions. I'm wondering if I can apply this approach to SAN backup / > > snapshot. But heard from Derby, it seems that there's no way to accept new > > transactions when backup is in progress. > > > Regards, > > > "InDeep" <ind...@indeep.com> wrote in message > >news:492b752e$0$18357$6c36adad@news.usenetserver.com... > >> Call your SAN vendor and ask them. > > >> With Oracle and EMC you set the database into hot backup mode, perform > >> the split mirror, then take the database out of hot backup mode. > > >> Something tells me it will be onmode -c block or onmode -c unblock as the > >> equivalent.  I tried this on my own test box, then went to Google to see > >> if I was on the right track.  You can test this on a developer instance to > >> see how it works.  I don't have a SAN handy to test on so you'll have to > >> script on your own.  Whatever SAN you use, the terminology will be > >> something > >> like 'split mirror' or BCV. > > >> onmode -c block > >> onstat> > >> IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days > >> 05:51:53 -- 39728 Kbytes> >> Blocked:ARCHIVE > > >> . > >> . do the split mirror here > >> . > > >> onstat > >> onmode -c unblock> > >> IBM Informix Dynamic Server Version 11.50.FC2DE -- On-Line -- Up 2 days > >> 05:52:52 -- 39728 Kbytes > > >> See also: > > >> =========== > > >>http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=10...> > >> "Look into the command: onmode -c block > >> You run this, and it does a checkpoint and blocks any more activity to the > >> disks. You then split off the bcv mirror. Because you did a checkpoint, > >> the split copy will be consistient at the time of the checkpoint. > >> To re-enable disk activity, do: > >> onmode -c unblock> >> I believe there is a white paper on Informix's website about this." > > >> =========== > > >> You can search Google for 'Informix BCV' or 'Informix split mirror' > >> and get more info. > > >> -ID- > > >> vt wrote: > >>> Hi all Informix experts, > >>>  i would like to put the Informix DB v9.x on SAN and take snapshots daily > >>> so that in case there is data corruption, I can rollback to previous > >>> version. However, I found Informix is a bit different from Oracle and > >>> Sybase as they have backup modes but Informix doesn't have. (Correct me > >>> if I'm wrong) > >>>  I did do some researches on the Internet and found a utility called > >>> onbar. Can I use this command to temporarily freeze the DB before I take > >>> a snapshot on the SAN so that the snapshot taken will have no integrity > >>> issue? If so, during the snapshoting, where will the new transactions go? > >>> Will the new transactions be temporarily stored on somewhere else? Thanks > >>> a lot in advance. > >>>  Regards, vt- Hide quoted text - > > - Show quoted text - Hi, Change the process from Indeep slightly. Here's how we do it: Shutdown DB on backup server Do resync from PRODUCTION to BACKUP When all copies are in sync do onmode -c block check all copies are done split mirrors off onmode -c blockdone This way you dont have to wait for the copiues to be done (which can take upto 8 hours).users can still work on prod. You only block the instance on PROD for the duration of the split, 15 seconds the users experince lag. Cheers

Hi, I'm running a standalone Informix on SUN V880. But I have another spare SUN V880, not in use yet. Do you mean I should setup another Informix (as backup host) on the spare machine, and mirror the DB on production host to the backup host? Regards, vt <14informix@gmail.com> wrote in message news:d2b17e9f-e195-42f5-8d9e-0b652fbf383a@t3g2000yqa.googlegroups.com... On Nov 25, 7:14 am, InDeep <ind...@indeep.com> wrote: Hi, Change the process from Indeep slightly. Here's how we do it: Shutdown DB on backup server Do resync from PRODUCTION to BACKUP When all copies are in sync do onmode -c block check all copies are done split mirrors off onmode -c blockdone This way you dont have to wait for the copiues to be done (which can take upto 8 hours).users can still work on prod. You only block the instance on PROD for the duration of the split, 15 seconds the users experince lag. Cheers

"vt" <peace-and-joy@hotmail.com> wrote in message news:gggc5u$1n2r$1@news.hgc.com.hk... > Hi, > > I'm running a standalone Informix on SUN V880. > But I have another spare SUN V880, not in use yet. Do you mean I should > setup another Informix (as backup host) on the spare machine, and mirror > the DB on production host to the backup host? No, just do what InDeep and Jarold said. You don't need to call EMC, and you don't need to use onbar (at this point). I don't think 14informix added anything new (and didn't really understand his bit about "Shutdown DB on backup server" (I assume as soon as the split is complete he mounts the split database disks on a backup server, which immediately destroys his capability of rolling forward subsequent logs)) but he did helpfully clarify the point that the onmode -c block/unblock operation need only be used during the *split*, not the sync as well - 2-3 seconds for me on a 1TB database on Symmetrix. Where you would need onbar is if you need to doa restore then log roll-forward: you combine onbar (probably ontape can be used too) with Informix's "external restore" functionality to roll forward any backed-up. post-split logical logs.

Good call, forgot about the sync before the split. I scripted one of these about 3 months ago, it runs flawlessly every night unattended, and I forgot about the sync. ( Since it runs so well I was rewarded with admin'ing a JBOSS project! :-( The bottom line is it should be scripted. ) VT, are you familiar enough with the EMC BCV process? Like I said before Informix makes it easier than Oracle. In Oracle I have to run SQL scripts and do a lot of return-code management to manage the database, in Informix it's easier because of the onmode command on the command-line. I think in Oracle they actually have to set up their instances a certain way to do hot backups (I'm not an Oracle DBA) . Good luck with it. -ID- vt wrote: > Hi, > > I'm running a standalone Informix on SUN V880. > But I have another spare SUN V880, not in use yet. Do you mean I should > setup another Informix (as backup host) on the spare machine, and mirror the > DB on production host to the backup host? > > Regards, vt > > <14informix@gmail.com> wrote in message > news:d2b17e9f-e195-42f5-8d9e-0b652fbf383a@t3g2000yqa.googlegroups.com... > On Nov 25, 7:14 am, InDeep <ind...@indeep.com> wrote: > > Hi, > > Change the process from Indeep slightly. > > Here's how we do it: > > Shutdown DB on backup server > Do resync from PRODUCTION to BACKUP > When all copies are in sync > do > onmode -c block> check all copies are done > split mirrors off > onmode -c block> done > > This way you dont have to wait for the copiues to be done (which can > take upto 8 hours).users can still work on prod. You only block the > instance on PROD for the duration of the split, 15 seconds the users > experince lag. > > Cheers > >

Neil Truby wrote: > > "vt" <peace-and-joy@hotmail.com> wrote in message > news:gggc5u$1n2r$1@news.hgc.com.hk... >> Hi, >> >> I'm running a standalone Informix on SUN V880. >> But I have another spare SUN V880, not in use yet. Do you mean I >> should setup another Informix (as backup host) on the spare machine, >> and mirror the DB on production host to the backup host? > > No, just do what InDeep and Jarold said. You don't need to call EMC, > and you don't need to use onbar (at this point). I don't think > 14informix added anything new (and didn't really understand his bit > about "Shutdown DB on backup server" (I assume as soon as the split is > complete he mounts the split database disks on a backup server, which > immediately destroys his capability of rolling forward subsequent logs)) > but he did helpfully clarify the point that the onmode -c block/unblock > operation need only be used during the *split*, not the sync as well - > 2-3 seconds for me on a 1TB database on Symmetrix. > > Where you would need onbar is if you need to doa restore then log > roll-forward: you combine onbar (probably ontape can be used too) with > Informix's "external restore" functionality to roll forward any > backed-up. post-split logical logs. If you are doing a Symmetrix sync ( not rsync ) you are pushing bits from prod to the other servers' disks, thusly you will need to shut down your target db or there will be corruption. Once the two are in-sync, it's time to split them. Once they are split they are each on their own again, the target can be brought back up.

"InDeep" <indeep@intoodeeptobetrue.com> wrote in message news:492c4336$0$23870$6c36adad@news.usenetserver.com... > Neil Truby wrote: >> >> "vt" <peace-and-joy@hotmail.com> wrote in message >> news:gggc5u$1n2r$1@news.hgc.com.hk... > > If you are doing a Symmetrix sync ( not rsync ) you are pushing bits from > prod to the other servers' disks, thusly you will need to shut down your > target db or there will be corruption. Once the two are in-sync, it's > time to split them. Once they are split they are each on their own > again, the target can be brought back up. The oiriginal poster wants the disk copy as a backup. not to use for any othr purpose. Therefore, I don't understand this idea of "shutting down the target server" and "bringing it back up". You just the leave the disk copy intact, maybe refreshing it nightly, for years on end without ever pointing a server at it *except* when you need to use it. The minute you bring Informix up on it the disk copy is destroyed as a potential source for a point-in-time restore using logical logs.

Hello vt, Everyone here has great information but onbar is the most difficult backup method to setup. Snap, too, takes some effort. Since you are new to all this, I recommend that you start with something easy. Just put "TAPEDEV /path_name/backup_filename" in the $ONCONFIG file and then run "ontape -s -L 0". This method is slow but reliable. -L.S.

vt wrote: > Hi all Informix experts, > > i would like to put the Informix DB v9.x on SAN and take snapshots daily > so that in case there is data corruption, I can rollback to previous > version. However, I found Informix is a bit different from Oracle and > Sybase as they have backup modes but Informix doesn't have. (Correct me > if I'm wrong) > > I did do some researches on the Internet and found a utility called > onbar. Can I use this command to temporarily freeze the DB before I take > a snapshot on the SAN so that the snapshot taken will have no integrity > issue? If so, during the snapshoting, where will the new transactions > go? Will the new transactions be temporarily stored on somewhere else? > Thanks a lot in advance. > > Regards, vt Just a bit more confusion... I'm not sure about the purpose of this... But you need to really think about it. Everything said before makes sense, and it will work. But what is your purpose? Let's see... - You'll have a database snapshot taken at a precise time. OnBar and ontape (much simpler) will also do that and ontape won't cost you anything. - What are you protecting against? What will happen if you take your snapshot at midnight and you hit major problems at 11H AM? Will you just go back to midnight image? Will that satisfy your business needs? - What if you drop a table by mistake, or simply do an update/delete with the wrong conditions? Will you simply revert the database for midnight snapshot? Will that satisfy you business needs? - Assuming your SAN storage makes a copy to you local facilities, what will happen to your database and your backup image? And to your business....? Unless these questions are being considered, I'd advise you start reading the IBM Informix Backup and Restore Guide. Is has a nice introduction to backup issues and considerations from a "policy" point of view. Then it drives you through all the technical stuff. It isn't too specific about SAN technologies, but it should mention the "external backup and restore" (onmode -c block/onmode -c unblock) Regards -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently...

"InDeep" <indeep@indeep.com> wrote in message news:492c27fe$0$1953$6c36adad@news.usenetserver.com... > Like I said before Informix makes it easier than Oracle. In Oracle I have > to run SQL > scripts and do a lot of return-code management to manage the database, in > Informix it's > easier because of the onmode command on the command-line. I think in > Oracle they actually > have to set up their instances a certain way to do hot backups (I'm not an > Oracle DBA) . It's not *that* difficult on Oracle. We use the technique for Oracle as well as Informix. Steps are: ALTER DATABASE BEGIN BACKUP; ALTER SYSTEM SUSPEND; /sbin/sync /sbin/sync <do EMC split> ALTER SYSTEM RESUME; ALTER DATABASE END BACKUP; and it works well.

Fernando Nunes wrote: > vt wrote: >> Hi all Informix experts, >> >> i would like to put the Informix DB v9.x on SAN and take snapshots >> daily so that in case there is data corruption, I can rollback to >> previous version. However, I found Informix is a bit different from >> Oracle and Sybase as they have backup modes but Informix doesn't have. >> (Correct me if I'm wrong) >> >> I did do some researches on the Internet and found a utility called >> onbar. Can I use this command to temporarily freeze the DB before I >> take a snapshot on the SAN so that the snapshot taken will have no >> integrity issue? If so, during the snapshoting, where will the new >> transactions go? Will the new transactions be temporarily stored on >> somewhere else? Thanks a lot in advance. >> >> Regards, vt > > > Just a bit more confusion... > I'm not sure about the purpose of this... But you need to really think > about it. Everything said before makes sense, and it will work. But what > is your purpose? Let's see... > > - You'll have a database snapshot taken at a precise time. OnBar and > ontape (much simpler) will also do that and ontape won't cost you anything. > - What are you protecting against? What will happen if you take your > snapshot at midnight and you hit major problems at 11H AM? Will you just > go back to midnight image? Will that satisfy your business needs? > - What if you drop a table by mistake, or simply do an update/delete > with the wrong conditions? Will you simply revert the database for > midnight snapshot? Will that satisfy you business needs? > - Assuming your SAN storage makes a copy to you local facilities, what > will happen to your database and your backup image? And to your > business....? > > Unless these questions are being considered, I'd advise you start > reading the IBM Informix Backup and Restore Guide. Is has a nice > introduction to backup issues and considerations from a "policy" point > of view. Then it drives you through all the technical stuff. It isn't > too specific about SAN technologies, but it should mention the "external > backup and restore" (onmode -c block/onmode -c unblock) > > Regards > Good points Fernando. BCVs are not appropriate for all situations, but the larger your database becomes, the more problematic it is to manage backups. A lot of sites are going to reconsider BCVs, expensive apps, and expensive storage in favor of more agile solutions. I think Informix is in a good position to meet a lot of those needs, but again, as I always say, apps drive databases, not the other way around. Until we start to see more apps on Informix, businesses will continue to use expensive storage, expensive databases, and expensive backups. -ID-