RE: Is there a downside to creating large chunks?

Hi Andy, Ah. So if you run 8 parallel onbar backup threads (or close to 8), that's more than plenty to fly through 120 GB. No real reason to increase the number of dbspaces. How is your i/o throughput?.... I run on EMC so I have not had to deal with the gritty details of i/o in a long time. It is talked about a lot out here/forums. You should be able to find info/advice on i/o in the archives if needed. You may need to look at how your chunks are laid out if you are having i/o issues or if you are changing that layer (disk/storage). How many chunks per dbspace do you have now, and how are your checkpoints? As Obnoxio said, reducing the number of chunks could impact your checkpoints. I believe he is refering to the 1 page cleaner/chunk theory. My memory could be bad, I have not had to do indepth perf tuning in... I don't want to say how many years ;-). You may be able to compensate some by your buffer cache and LRU min/max dirty.... But now you are talking IDS 11.5 and my last indepth tuning fun was on IDS 9.4.... Rules might have changed. If you are bored this weekend, you could give the performance manual a read or go to the member area of iiug.org (sign up for membership ...it's free) and look through the conference presentations... No doubt there are some good perf tuning presentations to be found. Happy weekend, NJ -----Original Message----- From: Bent_Andy [mailto:ABent@aetinc.com] Sent: Friday, July 18, 2008 2:14 PM To: Sebastian, Norma J. Cc: informix-list@iiug.org Subject: RE: Is there a downside to creating large chunks? We are upgrading to a new box / new Baan version / new Informix version so I have chance to reorganize the database. size = 120G currently have 8 data/index dbspaces backup = onbar with HP DataProtector Andy -----Original Message----- From: informix-list-bounces@iiug.org [mailto:informix-list-bounces@iiug.org] On Behalf Of Sebastian, Norma J. Sent: Thursday, July 17, 2008 5:25 PM To: Bent_Andy Cc: informix-list@iiug.org Subject: RE: Is there a downside to creating large chunks? I know this isn't your question... But how big is your database? How many dbspaces do you have now? And how do you do your backups? Increasing or decreasing the number of dbspaces can impact your backup performance. I ask because I used to run SAP on informix using onbar for backups... The more dbspaces I had, the more I could parallelize my backup. -----Original Message----- From: informix-list-bounces@iiug.org [mailto:informix-list-bounces@iiug.org] On Behalf Of Obnoxio The Clown Sent: Thursday, July 17, 2008 3:15 PM To: Bent_Andy Cc: informix-list@iiug.org Subject: Re: Is there a downside to creating large chunks? Bent_Andy said: > I am running a Baan ERP system on Informix 11.50/HPUX that has 5800 > tables. I want to spread these across 8 dbspaces. Is there a > disadvantage or advantage to creating 1 chunk per dbspace initially? You *could* get unexpectedly long checkpoints because there isn't enough distribution of data across multiple chunks. -- Bye now, Obnoxio http://obotheclown.blogspot.com/ _______________________________________________ Informix-list mailing list Informix-list@iiug.org http://www.iiug.org/mailman/listinfo/informix-list ============================================================ The information contained in this message may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any reproduction, dissemination or distribution of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by replying to the message and deleting it from your computer. Thank you. Tellabs ============================================================ _______________________________________________ Informix-list mailing list Informix-list@iiug.org http://www.iiug.org/mailman/listinfo/informix-list ============================================================ The information contained in this message may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any reproduction, dissemination or distribution of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by replying to the message and deleting it from your computer. Thank you. Tellabs ============================================================