Re: Do any of you have a policy on rebuilding indexes?

Study single level storage.

The issue of disk fragmentation was in the way back S/36 days (S/34 and
earlier). Single level storage with the advent of S/38 almost eliminated
that problem and now that we have fast access disk units it’s simply not a
concern at all. The storage management code in LIC deals with it, and
that’s way smarter about storage management than we will ever be.

The point behind reuse deleted records is when storage management is
writing new stuff to disk, it needs a continuous 4k block to write to. So
if it can’t find one, it moves things around to create it. If the file
reuse deleted records that’s already set up then it just updates that block
as needed. If your using HA at the disk level (PoweHA) it also marks that
block for replication.


The same type of single level storage is used in many hyper converged
system now as well.



On Thu, Mar 30, 2023 at 2:32 PM x y <xy6581@xxxxxxxxx> wrote:

In many transaction-oriented applications like order entry, most of the
disk I/O, especially writes and updates, is performed on recently-added
records often in very large files.

Does scatter-loading make a difference? Have the mechanics of IBM's
scatter-loading been published?

On Thu, Mar 30, 2023 at 8:44 AM <stefan@xxxxxxxxxx> wrote:

Disk fragmentation does not exist in IBM i due to single level storage,

so that's not an issue.

I disagree, single level storage will try to spread stuff evenly over the
available volume, however that does not prohibit fragmentation.
Look at help text for cmd STRDSKRGZ.

Best regards

Stefan

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Stefan Tageson
+46 732 369934
stefan@xxxxxxxxxx


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