IBM 000-8697 Manual de usuario descargar pdf (Pagina 564)

100

101

7-86 IBM Informix OnLine Database Server Administrator’s Guide

Option Descriptions

The number of active chunks and the number of existing chunks are listed.

The maximum number of chunks is speciﬁed as CHUNKS in the OnLine

conﬁguration ﬁle.

Occasionally, the timing of the tbstat -d command can affect the utility

output. Timing becomes a factor in two cases. The ﬁrst case occurs immedi-

ately after blobspace blobpages are allocated. The tbstat -d routine looks

directlyat thedisk toobtain blobpage statistics from theblobspace free-map

page.Ifblobpageswererecentlyallocated,itispossiblethattbstat-dwillnot

reﬂect the new allocation. This situation could arise if you execute tbstat -d

while the newest version of the blobspace free-map page remains in a

memory buffer and is not yet ﬂushed to disk. (Refer to page 2-148 for more

details about the blobspace free-map page.)

The second case in which timing affects output occurs after blobspace

blobpages are freed. The tbstat -d output does not show a blobpage as free

untilthelogicalloginwhichthepageorpagesweredeallocatedisfreed.That

is, if you modify blobs, tbstat -d shows that the pages where the obsolete

blobs are stored are stillin use until you backup and free the logical log that

contains the modifying statement.

Note that tbcheck -pB, which examines the disk pages, does not reﬂect this

timing nuance. If you delete a blob from a blobspace, tbcheck -pB output

reﬂects the freed space immediately. For this reason, output from tbstat -d

and tbcheck -pB could appear inconsistent.

For information about page reads and page writes, see tbstat -D.

-D Option

Use the -D option to display page read and page write information for the

ﬁrst50chunks in each dbspace.Allbut two of theﬁeldsthatappearinthe-D

output also appear in the tbstat -d output. You can interpret the two ﬁelds

that are unique to the -D output as follows:

page Rd is the number of pages read.

page Wr is the number of pages written.

1 2 ... 559 560 561 562 563 564 565 566 567 568 569 ... 701 702

Comentarios a estos manuales

Sin comentarios

IBM 000-8697 Manual de usuario Pagina 564

Comentarios a estos manuales

Relacionado con productos y manuales para Software de base de IBM 000-8697