| Title: | VAX and Alpha VMS |
| Notice: | This is a new VMSnotes, please read note 2.1 |
| Moderator: | VAXAXP::BERNARDO |
| Created: | Wed Jan 22 1997 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 703 |
| Total number of notes: | 3722 |
I have a customer that called and wanted to know something.
They are thinking about creating a secondary page/swap disk and
placeing secondary page and swap files on this disk. They wanted to
know the advantages and disadvantages if this page/swap disk was
SHADOWED. They are OpenVMS 6.1.
One of their thoughts of a disadvantage would be that when booting,
every time they booted this shadowed page/swap disk would do a merge.
They wanted to know if there was a way to prevent this from happening,
could they do something prior to shutdown?
Thanks in advance
Mark Antry
Mission Critical Support Team
GOLD/VMS
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 546.1 | EVMS::KUEHNEL | Andy K�hnel | Tue Apr 29 1997 12:49 | 12 | |
advantage:
A disk error during a hard pagefault taken in kernel mode will
cause a bug check. A shadow set greatly reduces the probability
of this scenario.
disadvantages:
Performance suffers. I can't think of a (reasonable) way to avoid
merge during startup, and shadowing generally isn't the best performer
for write-heavy applications. Paging/swapping usually involves
about as many writes as reads.
| |||||
| 546.2 | In a Cluster? | STAR::ATOZ | John J. Andruszkiewicz | Thu May 15 1997 07:50 | 10 |
You did not mention if this was a stand alone system, because that will make a difference - in the time it takes to do the necessary merge. For example, if another node has that virtual unit mounted, on controllers that can do write logging, then when the first system stops, the other system will do an assisted merge ( a.k.a. mini merge ) on that virtual unit. Regards, John | |||||