Re: Informix and RAID
craig, > Are there any whit-papers or other info on configuration of a data > wharehouse and RAID? I will be configuring an 8.2 server and am > considering hardware RAID over fragmentation. Any suggestions? i'm only going to touch on this, as it is a big subject, and will need some research on your part if you aren't already familiar with this, but informix fragmentation and the striping that happens with raid are not the same thing at all. fragmentation takes a table and breaks it up into a number of smaller tables, where you place each of those "fragments" into it's own dbspace. the fragmentation has different strategies, but is usually done on a column, (i.e. id > 0 and id < 100000 in dbspace1, id >= 100000 and id < 2000000 in dbspace2, etc...). what this does is allow the engine to search for the data and do any processing to the data it recieves in parallal. if you have your table in 1 dbspace, the engine will use 1 scan thread to get the data, if you have 157 dbspaces, it will use 157 scan threads to get the data. imagine reading a 100,000,000 row table from one disk, with one thread doing the work. now if you are using raid, then you have many disks doing the work, so your data is coming back faster, but it is still being channeled through 1 scan thread, 1 small pipe. if you set your raid scheme and your fragmentation up correctly, you will have many disk heads bouncing around ro return your data from disk, but it will be returning the data to many threads that will actually process it. big topic, but you can't run a large data warehouse without fragmentation. (of course you *can*, but you won't see nearly the performance unless you do a lot of unnecessary stuff). as far as white papers, they abound, but i don't know where they are off hand, as it has been a while. i would look in the faq for this newsgroup http://www.iiug.org/techinfo/ and i would just do a search on any of the search engines. hope this helps, mickm -- ----------------------------------------------------------------------- This is a signature file. This is only a signature file. Had this been an actual piece of useful information, you would have been instructed on what to do with it. -----------------------------------------------------------------------