RE: IDS 9.40 migration-question
snagnews@freenet.de wrote
> > >
> > > 4.) are big-chunks better than 2GB-chunks (because we
> have already
> > > created 2GB-Volumes over the Tru64 5.1B - LSM
> volumemanager)
> >
> > One question should be "do I need to use LSM for striping and
> mirroring
> > or can I just use Informix mirroring and split my drives
> over several
> > dbspaces avoiding the need for LSM all together"
>
> I prefer the use of hardware raid by raid-controller, we have
> an MSA30-Box with Raid-Controller and will not use LSM for
> striping/mirroring. The only thing is, that LSM is able to
> split large disks into several chunk-volumes of 2 GB (was
> needed by Informix <
> 9.xx)
>
I would suggest LSM is an overhead that is sucking CPU resource that you
do not need. Take it off completely and use raw disk directly from the
OS. In this case you do need an offset.
> > >
> > > 5.) if we put the 300 GB rootdbs in the first chunk, and
> all chunks
> > > reside on the same raid-box, is there a reason not to put physdbs
> > > and logsdbs on the same chunk with defining the
> offset?
>
> > You have gone from 70GB to 300 GB ? How many disks ? I would create
> > multiple dbspaces and have physbs on a separate spindle
> from rootdbs.
>
> Sorry, i've made a mistake, the rootdbs is 300 MB, not 300 GB.
>
> On the two disk-boxes, we have hardware-striped and mirrored
> 16 disks with 36 GB and 1 hot spare disk. This disk we have
> partitioned in 3 partitions, one for the production-database,
> one for test purposes and one for our arch2disk with
> filesystem. The database-partitions we have encapsulated as
> LSM disks and these db-partitions we have splitted in 2GB
> volumes. All runs on the same physical hardware. This is the
> hardware, we use.
Little benefit in 2GB chunks any more. Use your Storageworks software to
partition your raidset into multiple partitions (max 16). I would
suggest 3 partions. You can then use disklabel to create up to another 7
partitions(chunks) of any size on each of these for each of your
environments.
I can see no benefit in using LSM at all. You just need to get used to
using the Storageworks commands instead of LSM.
I will send some sample scripts directly that set up the partitions.
> > > 6.) Should the rootdbs on a volume over a volumemanager begin on
> > > offset 100?
> >
> > If you are using LSM that takes care of the offset, if using raw
> disks
> > directly you do need the offset.
>
> We think LSM takes care of the offset. But we don't really
> know it. In which way we can do a check that the rootdbs is
> damaged, if we use the offset of 0.
>
Set up rootdbs as the first chunk. Initialise the instance and do a
dbimport and dbexport. You should see the rootdbs go down fairly quickly
if you should have set an offset.
Colin Bull
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