| Title: | AdvFS Support/Info/Questions Notefile |
| Notice: | note 187 is Freq Asked Questions;note 7 is support policy |
| Moderator: | DECWET::DADDAMIO |
| Created: | Wed Jun 02 1993 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1077 |
| Total number of notes: | 4417 |
Hi all.
I'd like to know if there is a kind of documentation where all the
inner ADVfs structures are explained and where the output from some
commands such as vods, advfsstat, etc. is explained.
I'm trying to do the performance of some ADVfs filesets and all the
things I can do (according to the Digital UNIX Performance
documentation) is to run some commands such as 'showfile', 'defragment'
and 'balance'. By the way, which is the reason the 'Perf' field in the
'showfile' command output has different values?. I thought that when a
file has more than one extent, the Perf is always less than 100% and,
the more extents it has, the lesser the value in the 'Perf' field.
However, I have seen some database files with lots and lots of extents
and with 100% at the 'Perf' field.
I'll be very grateful if somebody could answer me the two questions
above.
Thanks in advance.
Regards.
Ana
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1072.1 | DECWET::LOWE | Bruce Lowe, DECwest Eng., DTN 548-8910 | Mon Jun 02 1997 11:12 | 9 | |
re: question 1 - There are no internals design documents available for the AdvFS data structures. Questions about the commands you mentioned, and others, are addressed in the man pages (version 4.0), and in the AdvFS "Guide to File System Administration" (AA-QTPZA-TE). I will see about getting more info re: question 2. | |||||
| 1072.2 | Some info on "Perf" | DECWET::LOWE | Bruce Lowe, DECwest Eng., DTN 548-8910 | Mon Jun 02 1997 15:26 | 9 |
This field is produced via a rather peculiar set of calculations, which involves several variables, including number of extents. However, the total number of files affects it as well, and in the special case where there was only a single very large file, it would always be 100%, regardless of how many extents that file had. Does your domain/fileset with the large database files contains a small total number of files? | |||||
| 1072.3 | DECWET::MARTIN | Mon Jun 02 1997 16:29 | 54 | ||
Regarding showfile's "Perf" of 100% on a database file with many extents:
If the database file is a sparse file, where each extent is separated from
adjacent extents by a hole, then it's as efficient as it can be.
In the following example, each 8 or 9 page extent is separated from the next one
by a 6 or 7 page hole. (And no, I can't explain why it's a 97% Perf instead of
100%.)
--Ken
lister:/sparse# showfile -x 8large_sparse
Id Vol PgSz Pages XtntType Segs SegSz Log Perf File
e.8001 3 16 282 simple ** ** off 97% 8large_sparse
extentMap: 1
pageOff pageCnt vol volBlock blockCnt
7 8 3 42016 128
21 8 3 42144 128
35 8 3 42272 128
49 8 3 42400 128
63 8 3 42528 128
77 8 3 42656 128
92 8 3 42784 128
106 8 3 42912 128
120 8 3 43040 128
134 8 3 43168 128
148 8 3 43296 128
162 8 3 43424 128
177 8 3 43552 128
191 8 3 43680 128
205 8 3 43808 128
219 8 3 43936 128
233 8 3 44064 128
247 8 3 44192 128
261 9 3 44320 144
276 8 3 44464 128
290 8 3 44592 128
304 8 3 44720 128
318 8 3 44848 128
332 8 3 44976 128
346 9 3 45104 144
361 8 3 45248 128
375 8 3 45376 128
389 8 3 45504 128
403 8 3 45632 128
417 8 3 45760 128
431 8 3 45888 128
446 8 3 46016 128
460 8 3 46144 128
474 8 3 46272 128
488 8 3 46400 128
extentCnt: 35
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