Re: disk layout/striping questions part 2

Any recommendations for the stripe setup on an Aix machine, i.e. 7.3 or better, using a LVM? Thanks, Nick On Tue, 25 May 1999, Art S. Kagel wrote: > Marc Hopkins wrote: > > > > We have a very similar setup, and I am currently testing the performance > > between OS Striping and Informix Fragmentation. > > HPUX 10.20 > > Informix 7.30 > > HP K420 4 processors > > 1 GB RAM > > 125 GB DB > > > > It seems to me that you have two choices. > > First, you could stripe at the Logical Volume level, creating stripes of > > 2GB, which you would then allocate to the database as chunks. So the chunks > > would be striped. > > > > Secondly, you could have several disks, and create a dbspace on each one. > > You could then fragment by round robin, using the dbspaces that are each > > located on a separate disk. Informix distributes that data evenly across > > the dbspaces The advantage of using Informix fragmentation, is that you can > > have multiple threads working at the same time, so if you had a table > > fragmented across 4 dbspaces(which are on different disks), you could have 1 > > thread searching each dbspace simultaneously, basically doing a parallel > > scan. This would also be beneficial as you have 4 cpu's, so each thread > > would not have a dedicated CPU. This seems like it would be faster, but I > > haven't reached that level of testing yet. Anyone else have arguments > > either way? > > I say do both! Stripe and mirror at the OS level (or firmware better) > and then fragment the table to allow multiple threads to work and to > permit fragment elimination to speed queries and not have to worry that > you may be hitting one fragment harder than the rest and beating on > that one drive because the striping and mirroring are spreading the > work around to, in Allen's case, 8 drives. > > Art S. Kagel >