Re: Informix 7.1 on Digital UNIX - raw or cooked?

Guys - There is virtually no chance this will happen - a database of any size would be corrupted every time a system came down ungracefully if the old buffer cache problem was an issue. Something would always be "in transit" to the disk. Probably 80-90% of Oracle installations use cooked files, and as woeful a bucket of bolts as it is, it's not even bad enough to screw this up. The reasoning is any DBMS that's worth a darn always opens the unix files they're using with a flag set to force synchronous writes to the file. So it really is mostly a performance and convenience issue. So let me address that - performancewise - raw is I gather almost always faster, usually substantially - I think Art Kagel has done some tests showing 30-50% on Solaris, I would guess YMMV, but you get the idea. As to convenience, if you're using the informix backup utilities (and you should be...), raw is as easy to deal with as cooked. If you're an oracle junkie and insist on rolling your own, well, good luck to you. Informix has always "preferred" raw to cooked, and I suspect Informix spends more time and effort tuning raw kernel asynch I/O than anything else. Of course, if you were really serious about doing this right, you would be using a more current engine release (this is a new install isn't it??), and probably a different HW/OS combo (ducking for cover...;-). Greg "boy I love my ISP alter ego, I can be as big a wisea$$ as I want to be..." Ashby, David wrote: > > The decision to go raw or cooked should not just be based on > performance. A more important consideration in my opinion is > recoverability. With a cooked file system IO's are fed to the OS for > writing, in a worst case scenario the following could happen: > - the server crashes > - Informix believes that a buffer has been written to disk > - but the OS has cached it and it has not been written > - when Informix is brought back online it does not recover the > suspect page > > If you can use KIO with raw chunks I believe that the OS cache is not > used. > > Regards, > David Ashby > > -----Original Message----- > From: mail [mailto:jcubero@iag.net] > Sent: Tuesday, 15 September 1998 4:11 > To: Informix-List > Subject: Informix 7.1 on Digital UNIX - raw or cooked? > > I am running Informix 7.1 on Digital UNIX 4.0, and getting ready > to set up a > new dB with 8 gB of RAID-1 disk space. My question is whether > I'm better > off using raw or cooked devices. I've heard that Digital has > great Disk > I/O, and I might be better off running cooked. Can anyone > confirm/deny > this, or advise as to which way to go?