Re: Using SSD with IBMi V7R1

[Luis Rodriguez <luisro58@xxxxxxxxx>]

Gad,

I would like to help you more regarding SSDs. Nevertheless, unfortunately
we don't have them in our shop. Although we still have an old i5-520 (V5R3)
for legacy and BI purposes, about 3-4 years ago our company converted to
the SAP/Oracle/HP environment.

All the above stated notwithstanding, the IBM i is still my favorite
platform, and I like to keep abreast on new developments.
Regarding to the KEEPINMEM parameter, it was introduced (AFAIK) with 7.1.
Let me quote you the IBM 7.1 Technical Overview Redbook:

**********

*The KEEPINMEM parameter specifies whether the data or an access for a file
member is*

*brought into a main storage pool by the SQL Query Engine (SQE) when the
data is used in*

*the query to improve the performance. When you specify *YES for this
parameter, the Query*

*Options File (QAQQINI) parameter MEMORY_POOL_PREFERENCE (see 6.4.15,
“QAQQINI*

*properties” on page 150) specifies the preferred main storage pool to be
used.*

* *

*This function applies only during the run time of a query, and might
therefore be substituted*

*for the Set Object Access (SETOBJACC) command that puts the table or index
in memory in a*

*static function. After the query completes, the memory might be freed
again, contrary to the*

*effects of the Set Object Access (SETOBJACC), where you need to clear it
using the *PURGE*

*option on the Storage Pool (POOL) parameter of the command.*
**********
So, while it has certain similarities to the SETOBJACC it´s not quite the
same thing, as it seems to be a little more dynamic and specific to a
particular query. Also, this parameter would work in any kind of DASD, SSD
or not (and, although a SSD is quite fast, I suppose that anything residing
in main memory should be faster still, so *maybe* this still is valid in a
SSD world).


Best Regards,

Luis Rodriguez
IBM Certified Systems Expert — eServer i5 iSeries