| Title: | FOCUS, from INFORMATION BUILDERS |
| Moderator: | ZAYIUS::BROUILLETTE |
| Created: | Thu Feb 19 1987 |
| Last Modified: | Mon May 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 615 |
| Total number of notes: | 1779 |
I am involved in a project benchmarking FOCUS applications on a
MicroVAX II and a 3500. I know next to nothing about FOCUS so please
excuse my ignorance:
I have been told that FOCUS applications will run faster when the
data files are on a disk with a disk cluster size of 8 blocks.
(I think this has something to do with the files always having
4Kb = 8 block records). This sounds a little fishy to me so I thought
I'd ask the experts. Is there any truth to this?
Jeffrey Marsh
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 10.1 | cluster size info | FDCV19::RYAN | Tue Oct 27 1987 17:42 | 16 | |
The answer is yes.
FOCUS stores everything in pages of 4096 bytes. However, VMS/RMS
reads a single FOCUS page in 3 I/O's - because VMS reads everything
in 512k chunks. Thus, a cluster size of 8 means than a single page
is read with 1 I/O instead of 3. A cluster size of 16 means that
two pages are read into memory instead on one.
Large file/database storage is more efficient with larger cluster
sizes; however the inverse is also true: a larger cluster size means
that even a one character file is store in the minimum cluster size
(e.g 8 or 16). Hence, a one line login.com file on a cluster size
of 8 would be stored in 8 blocks.
-rpr-
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