Re: Informix Disk Layouts.

I would recommend striping as well. I did some benchmarking of striped vs. non-striped RAID sets. I performed R/W intensive operations on both RAID 0+1 (5+5) and RAID 5 (5+1) sets. In general, RAID 0+1 out performed RAID 5 in Writes but Read operations were much closer. I would urge you to shy away from RAID-5 in OLTP; my reserver for RAID-5 is reduced in a DSS environment. As for the number of members in a stripe sets, I am not sure. A general rule of thumb is that the more disks you stripe across the better the performance. The trade-off hear is RAS. You mention that Solaris metadevice limit is 6. Not sure where you got that from? I am running Solaris 2.6 and SEVM 2.5. I did some RTFMing, but couldn't find the reference. A little help would be nice ;-). Steve Romankiw Murray Wood wrote: > My $0.02 > > I would stripe. With 6 disks probably 2 stripes of 3 disks. > Place high usage chunks near the middle. > Place things that occur together on opposite stripes (data on one stripe, > index on the other, for example. root on one stripe, logs on the other) > > One thing that may sway you to something else... Which volume manager are > you using and How many slices can you put the disk into? (The limit if > Solaris metadevice is 6 slices). > > The alternative is able to double guess how the application is used and to > even the load over all drives. I dont think that is practical with my > application(s) and users. > > Murray Wood > > -----Original Message----- > From: Michael Brizendine [SMTP:michaelb@pegsinc.com] > Sent: Friday, June 18, 1999 9:57 AM > To: informix-list@iiug.org > Subject: Informix Disk Layouts. > > All, > > We have the opportunity, at my company to move from Informix 7.24 on an > E4000 to 7.31 on an E6500. I feel like we have a good grip on the cpu > and memory aspects but not on the disk configuration. > > For the past 3 years I have been successful at handling I/O problems by > breaking tables accross muliple dbspaces, and disks. Our current setup > is about 20 - 2gig disks. > > With the new box we have a drive array that gives us 17 - 9 gig disks. > Once everything is said and done I know have about 6 disks to spread all > my raw space accross instead of about 15. > > There are 2 disinct approaches we are looking at testing, and I would > like your feedback on both. The 1st approach is to stripe everything > accross multiple disks (4-6). This is what Sun recommends as well as > out System Admins. This is not something that I think highly about > because I feel like I have lost control of where my data is and how to > decide where my contention is as far as the dbschema goes. The 2nd > approach is to break everything accross disks the way we have to date, > only adding detach indexes, and fragementation strategies to a couple of > our top i/o tables. This has always been my approach and the > recommendation that I feel like Informix has given me. > > I would appreciate any comments, help you might have. I can give us > much detail about our system as any of you all need. Thanks in advance. > > Michael Brizendine > Strategy DBA > Pegasus Systems Inc. > 214-523-0143