Re: dbsizes/chunk sizes/raw partitions

moldovan@mmsi.com wrote: > > We recently did a new install of SAP R/3 3.0f on a Solaris 2.51 > system. I used the Solaris DiskSuite tools to mirror ten 4.2 > Gig drives into five 4.2G 'metadevices'. These raw metadevices > where set up for the Informix 7.2 DB for SAP. I noticed as > I increased some dbspaces that I did not seem to have as much > space as I though I should. It appears to me that I only have > about one half of my raw space available to Informix. Is there a > problem with Informix using a 4.2G 'raw' device? Yes. Informix can only address devices up to 2GB (2097150K) so you will have to redefine your 'metadevices' into 10 2GB 'metadevices', though this will waste .2GB per mirror. You could combine the separate mirrors into a single stripe set (21 GB) then devide this into 10 2GB and 1 1GB 'metadevices'. We do this on DG/UX with Clariion Arrays and the performance is great. I believe that Solaris can handle this level of indirection also. BTW if you do this work with Sun. On DG the performance of the stripe segments is highly dependant on the starting position of each segment within the stripe set (each must start on a 16K boundary or performance suffers for one example). We had to create chunks of 2096640K rather than the Informix maximum size to avoid waste between segments or performance degradation. This may also be true for Sun. Art S. Kagel