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The standard query used to see them all (as sys or internal):
select x.inst_id,
x.indx+1 num, ksppinm name, ksppity type, ksppstvl value, ksppstdf ISDEFAULT, decode(bitand(ksppiflg/256,1),1,'TRUE','FALSE')ISSES_MODIFIABLE,
decode(bitand(ksppiflg/65536,3),1,'IMMEDIATE',2,'DEFERRED',3,'IMMEDIATE','FA LSE')ISSYS_MODIFIABLE, decode(bitand(ksppstvf,7),1,'MODIFIED',4,'SYSTEM_MOD','FALSE')ISMODIFIED,
decode(bitand(ksppstvf,2),2,'TRUE','FALSE')ISADJUSTED, ksppdesc DESCRIPTION
This is something I found on MetaLink a few years ago. I looked for an updated version but couldn't find one:
Oracle: Explanation of Oracle undocumented parameters Last Updated on 01-JUL-97 The following is a list of undocumented parameters.
disk; although, it may crash the foreground of the instance. It will help
catch stray writes in the cache. When you try to write past the buffer
size in the sga, it will fail first with a stack violation. It seems that the db_block_cache_protect has a significant performance
overhead. Preliminary testing shows that it has considerable overhead
(a single update took twice as long with the parameter set to TRUE).
2. _db_block_compute_checksums
There is another new init.ora parameter, DB_BLOCK_COMPUTE_CHECKSUMS, that
controls whether a checksum is put into every block before the block is
written to disk. The default is FALSE. A block read validates an exiting checksum whether or not this option is enabled. A block is marked
as corrupt if a checksum fails.
It helps determine corruption due to hardware problems. The incarnation
number and the sequence number are added to the end of the block to help catch corruption.
If the problem (corruption) is in the middle of the block this test will not detect it. To detect this problem a checksum may be generated in the block header before every write and verified on every read.
3. _db_block_hash_buckets= "Number of database block hash buckets"
The number of hash buckets is
prime.
I would tend not to change it unless there is latch contention on the
hash
chains. raising it to equal the number of buffers would clearly remove any
contention (basically, this is just saying that each buffer lives on its own
hash chain). Having it set too small would mean that we might have to scan
over lots of buffers to find the one we want. I think the default is to
make it 1/4 of the total number of buffers
4. _db_block_multiple_hashchain_latches
"Use one latch per hash chain"
5. _db_handles
"System-wide simultaneous buffer operations"
6. _db_handles_cached
"Buffer handles cached each process"
7. _wait_for_sync
" Wait for sync on commit "
Wait_for_sync is an oracle generic parameter which, when set to
false, will allow the system to complete commits without waiting
for the redo-log buffer flushes to complete.
8. _db_block_max_scan_cnt="Maximum number of buffers to inspect when
looking for free buffer"
DB_BLOCK_MAX_SCAN_CNT is an init.ora parameter which specifies
the number of unavailable buffers a process should scan before signaling
DBWR to write dirty buffers from the buffer cache to disk.
9. _db_writer_scan_depth
"Number of LRU buffers for dbwr to scan when looking for dirty buffers"
10a. _db_writer_scan_depth_increment
"Add to dbwr scan depth when dbwr is behind"
10b. _db_writer_scan_depth_decrement
Subtract from dbwr scan depth when dbwr is working too hard
to
increase.
DBWR Free Low is the number of times DBWR is invoked because a user
process found at least DB_BLOCK_WRITE_BATCH/2 buffers on the dirty list.
This parameter specifies the number of blocks which should be written to
disk at one time.
This parameter should only be increased until the statistics
Write Complete Waits and Write Wait Time show growth. Write Complete
Waits is the number of times a process waited for DBWR
to write a current block before making a change to a buffer.
and we were told to run without it.
during recovery. This code is enabed with a new init.ora parameter: _log_checkpoint_recovery_check=XXX, where XXX is the number of redo blocks to check. This is called in LGWR after every checkpoint. If the
init.ora parameter "_log_checkpoint_recovery_check" is zero (default) it does nothing. If it is a positive value then that many blocks of redo are scanned to see that the data file blocks on disk could be recovered if there was an immediate crash. This code was introduced to catch an elusive bug that results in OERI(3020) errors occasionally during crash recovery.
If it is a positive value then that many blocks of redo are scanned to see
that the data file blocks on disk could be recovered if there was an immediate crash. This code was introduced to catch an elusive bug that results in OERI(3020) errors occasionally during crash recovery. Checkpoint recovery check: this is the number of redo blocks that kcracl will verify after every LGWR generated checkpoint. Defaults to zero
for no checking. When opening the named offline log for redo application
and to recalculate future change thread switching this parameter is used.
file.
to prebuild before the copy to the log buffer. Increasing this parameter
reduces the time that the redo copy latch is held. This parameter should
not be modified if it is a single processor environment or there will be
memory contention.
22. _disable_logging
If this is true, redo records will not be generated -- no recovery is possible
if the instance crashes. It is mainly used for getting good benchmarking
results.
Default is false
23. _log_blocks_during_backup
TRUE value implies before any change is made to a db_block in the buffer
cache, a *complete image* of the block is copied to the redo redo log. (This explains why excessive redo would be generated for datafiles excessive redo would be generated for datafiles in hot backup
mode.) There is a new init.ora parameter, LOG_BLOCKS_DURING_BACKUP,
that controls whether block images ar written to the redo log during
hot backup.
Default is TRUE for VM, but port specific with the default defined in
sparams.h. This may beset to FALSE if the Oracle block size equals
the O/S physical sector sie or if it is otherwise ensured that hot
backup
reads consistent versios of blocks even if those blocks are being written
at the time. Put anther way, this may be set to FALSE on machines that
can guarantee the aomicity of a single block I/O request.
Default is true
Problem is due to split blocks.
24. _allow_resetlogs_corruption
Added new secret init.ora parameter to override error 1138.
When set to TRUE the
resetlogs option will be allowed even if there are hot backups that need
mor redo applied. Unless you are certain that absolutely all redo, includig
the online logs, has been applied, then a full export and import mst be
done to insure the database is internally consistant.
from 6.0 code
/* if we crashed/shutdown during a hot backup it is over now and we ** are no longer logging blocks. If they did a manual recovery ** followed by a NORESETLOGS then the hot backup recovery flag can ** be cleared. The hot backup recovery flag may alsoneed clearing ** if RESETLOGS was allowed because of _allow_resetlogs_corruption ** parameter. */
from the c file kcv.c 7.0 code
/* if the resetlogs option is in effect we save the highest checkpoint
for n index entry. The value determines the number of blocks to check on the freelist when looking for a reusable block.
26. _mts_load_constants
/* hidden init.ora to set server load balancing constants */ /* fill in load balancing parameters (from _mts_load_constants) */
determine that the mts is not optimal.
27. _mts_fastpath
/* hidden init.ora to enable dispatcher fastpath */ default is false
locks
default is 100
32. _row_cache_buffer_size
"size of row cache circular buffer"
default is 200
33. _messages
" message queue resources - dependent on # processes " The asynchronous message mechanism allows processes to send messages to each other. A process may send a message to a specified other process (always without waiting for a reply), may wait for a message to arrive on its queue, and may obtain the next message. Messages sent to detached processes are reliably delivered. Messages sent to foreground processes are reliably delivered as long as the process is active. The mechanism also permits sending of a simple "reply", which is a one-byte message without queuing. It should normally be used to reply to asynchronous messages, and this is a safer technique than regular messages for responding to foreground processes. This mechanism is not used in single process mode.
34. _cpu_count
ksb - Kernel Service Background processes
"number of cpu's for this instance"
CPU_COUNT has to be set on some platforms in order for Oracle to take
advantage of multi-processor system, on others it does not have effect
on
performance since load balancing between processors is handled by the o/s.
35. _debug_sga
/* Debug SGA, don't make the SGA a global section so we can set watchpoints
36. _enqueue_locks
ksq1 - Kernal Service enQueues (1) Definitions for enqueues client objects, "locks for managed enqueues"
37. _enqueue_hash
"enqueue hash table length"
38. _enqueue_debug_multi_instance
"debug enqueue multi instance"
KST is a trace facility used for "realtime" tracing of events. Below are defined KST macros that will enable the tracing of such things as latch operations, memory assignments, etc. Tracing is done to a per process circular buffer stored in the SGA. Access to these buffers is via fixed tables. Tracing is enabled for classes of events, particular events, and ranges of events. The tracing state may be dynamically changed with the following syntax "ALTER TRACING" - "ON" - Processes begin logging events using the current enabled events - "OFF" - Processes stop tracing - "ENABLE" <event_string> - Add in the events indicated in <event_string> to those which are being traced. - "DISABLE" <event_string> - No longer trace events specified by <event_string>
39._trace_buffers_per_process
Note that by default, tracing is NOT enabled. In order to enable tracing
at instance startup time, add _trace_buffers_per_process = 1
40. _trace_block_size
_trace_xxxxx (xxxxx = buffers_per_process, block_size, archive_start,
flushing, enabled, get_time_every, archive_dest etc.)These parameters are only there for debugging purposes. Customers or support will never have to use them.
41. _trace_archive_start
"start trace process on SGA initialization"
42. _trace_flushing
"TRWR should try to keep tracing buffers clean"
43. _trace_enabled
By default, tracing is NOT enabled. In order to enable tracing, _trace_enabled = true
44. _trace_events
If you wish to enable tracing of waits at instance startup time, you can
either
add the line '_trace_events = "WAT,ALL"' to init.ora or execute
'alter tracing enable "WAT,ALL"' in a sqldba session.
If you wish to limit tracing to specific events, you can use the
the following syntax:
alter tracing enable "WAT,<id>,<id>..."
where "id" is either a specific event number, or an event range
(event number 1 - event number 2).
45. _trace_archive_dest
"trace archival destination"
46. _trace_file_size
"trace file size"
default is 10000 blocks
47. _trace_write_batch_size
"trace write batch size"
default is 32
48. _rollback_segment_initial
"starting undo segment number"
Default is 1. DO NOT SPECIFY 0 AS THAT HAPPENS TO BE THE SYSTEM ROLLBACK
49. _rollback_segment_count
"number of undo segments"
default is 0
50. _offline_rollback_segments
If a rollback segment is not accessible because the file it is in is offline or corrupted, one can force the system to come up without the rollback segment by specifying the rollback segment in init.ora paramater '_offline_rollback_segments'. The system will come up by estimating the current system commit time since it cannot access transaction tble in the rollback segment. The system commit number is a conservative guess based on current time, the database creation time and the assumed transaction rate of 8000 tps. ONE MUST MAKE SURE THAT THE SYSTEM TIME IS SET CORRECTLY WHEN FORCING THE SYSTEM UP USING '_OFFLINE_ROLLBACK_SEGENTS'. A trace is written with information
about the estimated system commit number.
51. _corrupted_rollback_segments
Mark a rollback segment as corrupted.
52. _label_tag_cache_size
/* hidden size of the SGA label tag comparison cache (bitcache) */ "number of tags in the label tag comparison cache" default is 200
53. _trace_get_time_every
"Number of trace sequence numbers per call to slgcs()"
default is 200
54. _vms_bg_priority
"VMS process priority to give to background processes"
default is 4
55. _sort_use_os_files_as_temporaries
Use O/S files rather than temp segments for sorting.
56. _log_checkpoints_to_alert
Whether checkpoint messages should be written to alert.log or not. Turned
off in benchmarks.
57. _large_memory_system :
Used in internal benchmarks. Doesn't concern us.
"Configure system to use memory and save cpu cycles, paging, etc
default is false
58. _wakeup_timeout
This is WMONs sleeptime between checks of it's queue of processes to wake.
59. _latch_wait_posting
enable posting of processes that may be waiting for a latch after a process
frees the same latch (set this parameter to a value greater than one this parameter to a value greater than one for it to take effect).
60. _sql_connect_capability_code
allows database links from a pre-7.0.15 release to work with release 7.1.
It is necessary to set this parameter for database links from a V6 ?
Brian P. Mac Lean
Senior Oracle Database Administrator
OCPv8/Oracle Master
HomeBid.Com
8700 N. Gainey Center Drive
Scottsdale, AZ 85258
Tel:480.609.4624 Cel:602.617.6075 Fax:480.609.4646 Net:brian.maclean_at_homebid.com <mailto:Net:brian.maclean_at_homebid.com>
Who needs friends when you can sit alone in your room and drink?
-----Original Message-----
From: djordjej [mailto:djordjej_at_netcom.ca]
Sent: Monday, May 08, 2000 6:34 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: REF : _* initialization parameters (to all who have replied)
Some info you can find in Oracle Press, Oracle Performance Tuning, Tips&Techniques by Richard Niemiec.
Djordje
-----Original Message-----
From: Benhayoune khalid < benhayoune_at_maroclear.co.ma
<mailto:benhayoune_at_maroclear.co.ma> >
To: Multiple recipients of list ORACLE-L < ORACLE-L_at_fatcity.com
<mailto:ORACLE-L_at_fatcity.com> >
Date: Monday, May 08, 2000 3:19 PM
Subject: REF : _* initialization parameters (to all who have replied)
Excuse my poor English !
Think you for your replies.
What i need is not a short description of these parameters but a description like what we find in "Oracle Server : Reference" chapter 1 : initialization parameters or something more detailed.
Think you in advance.
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =charset=3Diso-8859-1">
<TITLE>_* initialization parameters</TITLE> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <META content=3D"MSHTML 5.00.2722.2800" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT color=3D#0000ff face=3DArial size=3D2><SPAN =class=3D138432314-09052000>The=20
_db_block_cache_protect <BR> On =
VMS, the=20
DB_BLOCK_CACHE_PROTECT mechanism has been made much =
<BR> =20
faster. During normal use, having it turned on shouldn't=20
be <BR> noticeable (the degradation =
is less=20
than 1%). Developers who <BR> =
link=20
non-share will need PSWAPM privilege to use this =
feature. =20
<BR> When DB_BLOCK_CACHE_PROTECT is turned on, =
developers may=20
either <BR> use the VMS mailboxes =
with the M=20
(MEMORY_LOG) command <BR> or they =
may just=20
examine the ring buffer in the PGA (index =20
<BR> SMPREI_, array SMPREB_) to determine what buffer =
requests=20
have <BR> been made=20
recently. <BR> =
DB_BLOCK_CACHE_PROTECT will=20
prevent certain corruption from getting to =20
<BR> disk; although, it may crash the foreground of =
the=20
instance. It will help <BR> =
<BR> catch=20
stray writes in the cache. When you try to write past the=20
buffer <BR> size in the sga, =
it will=20
fail first with a stack violation. =
<BR> It=20
seems that the db_block_cache_protect has a significant=20
performance <BR> overhead. =
Preliminary=20
testing shows that it has considerable overhead =20
<BR> (a single update took twice as long with the =
parameter=20
set to TRUE). <BR> <BR>2.=20
_db_block_compute_checksums <BR> =
There is=20
another new init.ora parameter, DB_BLOCK_COMPUTE_CHECKSUMS, that =20
<BR> controls whether a checksum is put into every =
block=20
before the block is <BR> written to disk. =
The=20
default is FALSE. A block read validates an =
<BR> =20
exiting checksum whether or not this option is enabled. A block =
is=20
marked <BR> as corrupt if a checksum =
fails. =20
<BR> It helps determine corruption due to hardware=20
problems. The incarnation <BR> number and =
the=20
sequence number are added to the end of the block to help catch=20
corruption. <BR> If the problem (corruption) is =
in the=20
middle of the block <BR> this test will not =
detect it.=20
To detect this problem a checksum may be <BR> =
generated=20
in the block header before every write and verified on =
every read. =20
<BR> <BR>3. _db_block_hash_buckets=3D "Number of =
database block=20
hash buckets" <BR> The number of =
hash=20
buckets is <BR> a) by default to be set to a =
prime=20
number; <BR> b) coerced to a prime =
if there=20
is an init.ora parameter setting. =
<BR> The=20
value, if not a prime number > 2, is rounded up to the next=20
highest <BR> prime. =
<BR> I=20
would tend not to change it unless there is latch contention on the =
hash =20
<BR> chains. raising it to equal the number of =
buffers would=20
clearly remove any <BR> contention (basically, =
this is=20
just saying that each buffer lives on its own =
<BR> hash=20
chain). Having it set too small would mean that we might have to=20
scan <BR> over lots of buffers to find the one =
we want.=20
I think the default is to <BR> make it =
1/4 of the=20
total number of buffers <BR> <BR>4.=20
_db_block_multiple_hashchain_latches =
<BR> =20
"Use one latch per hash chain" <BR> <BR>5.=20
_db_handles <BR> "System-wide =
simultaneous=20
buffer operations" <BR> <BR>6.=20
_db_handles_cached <BR> "Buffer =
handles=20
cached each process" <BR> <BR>7.=20
_wait_for_sync <BR> " Wait for sync =
on=20
commit " <BR> Wait_for_sync is an oracle =
generic=20
parameter which, when set to <BR> false, will =
allow the=20
system to complete commits without waiting <BR> =
for the=20
redo-log buffer flushes to complete. <BR> <BR>8.=20
_db_block_max_scan_cnt=3D"Maximum number of buffers to inspect =
when =20 <BR> looking for free buffer" = <BR> =20
<BR> and we were told to run without it. =20 <BR> <BR>14. _controlfile_enqueue_timeout =20 <BR> /* use parameter value (default is 900) */ =
<BR> /* System Parameter: control file enqueue =
timeout in=20
seconds */ <BR> <BR>15.=20
_db_no_mount_lock <BR> add hidden =
parameter=20
to not acquire mount lock <BR> If hidden =
int.ora=20
parameter _db_no_mount_lock is set to TRUE <BR> =
then no=20
mount locks are acquired when the the database is mounted =20
<BR> exlusive. This allows two databases with the =
same name to=20
be <BR> simultaneously mounted. Note that this=20
circumvents the mechanism <BR> to prevent two=20
simultaneous startups of the same database, and is =
<BR> =20
thus a dangerous parameter to set. This only affects ports that =20
<BR> ar compiled with the SYS_DFS option enabled =
(i.e. VMS=20
only). <BR> It does not get a mount lock on the =
database=20
name during startup. <BR> This allows 2 =
instances with=20
the same name to run on one machine <BR> <BR>16.=20
_log_checkpoint_recovery_check <BR> Check redo =
log after=20
checkpoints. <BR> Add debugging code to check =
the red=20
log after a checkpoint. This <BR> code is =
intended=20
to help find a problm that is generating ora-600 [3020] =20
<BR> during recovery. This code is enabed with =
a new=20
init.ora parameter: <BR> =20
_log_checkpoint_recovery_check=3DXXX, where XXX is the number of =
redo =20
<BR> blocks to check. This is called in =
LGWR after=20
every checkpoint. If the <BR> init.ora =
parameter=20
"_log_checkpoint_recovery_check" is zero (default) =
<BR> =20
it does nothing. If it is a positive value then that many blocks =
of =20
<BR> redo are scanned to see that the data file =
blocks on disk=20
could be <BR> recovered if there was an =
immediate crash.=20
This code was introduced <BR> to catch an =
elusive bug=20
that results in OERI(3020) errors <BR> =
occasionally=20
during crash recovery. <BR> <BR>17. =
_switch_on_stuck_recovery =20
<BR> REDO GENERATION HAS BEEN CHANGED SO THAT WE =
SHOULD NEVER=20
ENCOUNTER <BR> A CHANGE IN THE FUTURE OF THE =
BLOCK.=20
APPLYING REDO IN SCN ORDER NOW <BR> INSURES =
THAT CHANGES=20
ARE APPLIED IN INCARNATION/SEQUENCE # ORDER. THERE =
<BR> =20
IS A LOT OF CODE IN RECOVERY THAT IS NO LONGER NEEDED BECAUSE OF =
THIS =20
<BR> CHANGE. THIS INCLUDES THE CODE TO BACKUP AND =
RESCAN AFTER=20
REPAIRING <BR> CORRUPTIONS. THE CODE IS BEING =
LEFT IN TO=20
AVOID LARGE CHANGES JUST BEFORE <BR> V7.0 =
PRODUCTION=20
RELEASE. THE FOLLOWING WILL INSURE THE UNNEEDED CODE =20
<BR> IS NEVER EXECUTED UNLESS REDO WAS GENERATED BY A =
BETA=20
RELEASE OR THE <BR>SECRET <BR> INIT.ORA =
PARAMETER=20
_SWITCH_ON_STUCK_RECOVERY IS SET TO TRUE. <BR> =
Check=20
redo Log contents after checkpoint. This is called in LGWR after =20
<BR> every checkpoint. If this parameter is zero =
(default) it=20
does nothing. <BR> If it is a positive =
value then=20
that many blocks of redo are scanned to see <BR> =
<BR> =20
that the data file blocks on disk could be recovered if there was =
an =20
<BR> immediate crash. This code was introduced to =
catch an=20
elusive bug that <BR> results in OERI(3020) =
errors=20
occasionally during crash recovery. <BR> =
Checkpoint=20
recovery check: this is the number of redo blocks that =20
<BR> kcracl will verify after every LGWR generated =
checkpoint.=20
Defaults to zero <BR> <BR> for no =
checking. =20
When opening the named offline log for redo application <BR> =20
<BR> and to recalculate future change thread =
switching this=20
parameter is used. <BR> <BR>18.=20
_log_io_size=3Dredo log IO chunk size (blocks/write) =20
<BR> /* System Parameter: IO chunk size */ =20 <BR> 1. that the value is o/s dependent. =20 <BR> 2. if left at 0, the value will be automatically =
determined for each log <BR> =20
file. <BR> <BR>19. =
_log_buffers_debug =20
<BR> /* debugging: fill redo buffers with [well =
known] junk=20
after writes */ <BR> "debug redo buffers (slows =
things=20
down)" <BR> <BR>20. =
_log_debug_multi_instance =20
<BR> /* debugging : pretend multi-instance */ =20 <BR> "debug redo multi instance code" =20 <BR> <BR>21. =
determines the maximum size of a redo entry =
<BR> to=20
prebuild before the copy to the log buffer. Increasing this=20
parameter <BR> reduces the time that the redo =
copy latch=20
is held. This parameter should <BR> not =
be=20
modified if it is a single processor environment or there will be =
<BR> memory contention. <BR> =
<BR>22.=20
_disable_logging <BR> If this is =
true, redo=20
records will not be generated -- no recovery is =
<BR>possible =20
<BR> if the instance crashes. It is mainly used =
for=20
getting good benchmarking <BR> results. =20
<BR> Default is false <BR> =
<BR>23.=20
_log_blocks_during_backup <BR> TRUE =
value=20
implies before any change is made to a db_block in the =
buffer =20
<BR> cache, a *complete image* of the block is copied =
to the=20
redo <BR> redo log. (This explains =
why=20
excessive redo would be generated for =
<BR> =20
datafiles excessive redo would be generated for datafiles in hot =
backup =20
<BR> mode.) There is a new init.ora parameter,=20
LOG_BLOCKS_DURING_BACKUP, <BR> that controls =
whether=20
block images ar written to the redo log during =
<BR> hot=20
backup. <BR> Default is TRUE for =
VM, but=20
port specific with the default defined in <BR> =20
sparams.h. This may beset to FALSE if the Oracle block size =
equals =20
<BR> the O/S physical sector sie or if it is =
otherwise ensured=20
that hot backup <BR> reads consistent versios =
of blocks=20
even if those blocks are being written <BR> at =
the=20
time. Put anther way, this may be set to FALSE on machines =
that =20
<BR> can guarantee the aomicity of a single block I/O =
request. <BR> Default is true =20
<BR> Problem is due to split blocks. =20
<BR> <BR>24. =
_allow_resetlogs_corruption =20
<BR> Added new secret init.ora parameter to override =
error=20
1138. <BR> When set to TRUE =
the =20
<BR> resetlogs option will be allowed even if there =
are hot=20
backups that need <BR> mor redo applied. Unless =
you are=20
certain that absolutely all redo, <BR>includig =
<BR> the=20
online logs, has been applied, then a full export and import mst =
be =20
<BR> done to insure the database is internally=20
consistant. <BR> <BR> from =
6.0=20
code <BR> /* if we crashed/shutdown during a =
hot backup=20
it is over now and we <BR> ** are no longer =
logging=20
blocks. If they did a manual recovery <BR> ** =
followed=20
by a NORESETLOGS then the hot backup recovery flag can =20
<BR> ** be cleared. The hot backup recovery flag may =
alsoneed=20
clearing <BR> ** if RESETLOGS was allowed =
because of=20
_allow_resetlogs_corruption <BR> ** parameter. =
*/ =20
<BR> <BR> from the c file kcv.c 7.0 =
code <BR> /* if the resetlogs option is in effect we =
save the=20
highest checkpoint <BR> ** scn that we =
see, to be=20
used as the incomplete recovery scn. It only =
<BR> =20
** gets used if a resetlogs is done without any recovery. Only=20
backup <BR> ** control file recovery will =
be=20
allowed and it always rewrites the <BR> =
**=20
incomplete recovery scn. We use the highest scn we can find so=20
that <BR> ** new resetlogs scn will be =
greater=20
than anything in the database. <BR> ** =
This may=20
not be strictly true if the user sets =
<BR> **=20
_allow_resetlogs_corruption, and there is a fuzzy file. Note =
that =20
<BR> ** since resetlogs does not look at the log file =
headers,=20
datafile <BR> ** checkpoints are all we =
have to=20
look at. <BR> <BR>25. _reuse_index_loop =20
<BR> "number of blocks being examine for index block=20
reuse" <BR> /* secret system parameter to =
control how=20
agressive we should walk the <BR>free <BR> ** =
list when=20
attempting to reuse block - default is 5. <BR> =
** Set to=20
0 for fast index operation which is susceptible to growth, =20
<BR> ** Set to > 5 for slower index op but more =
agressive=20
in reusing blocks */ =
<BR> =20
Controls the amount of work done when looking for a block to =
reusse =20
<BR>for n index entry. The value =
determines the=20
number of blocks to =
<BR> =20
check on the freelist when looking for a reusable =
block. =20
<BR> <BR>26. _mts_load_constants =
<BR> =20
/* hidden init.ora to set server load balancing constants */ =20
<BR> /* fill in load balancing parameters (from=20
_mts_load_constants) */ <BR> * PID Controller - =
calculate control on number of servers using: =
<BR> *=20
control =3D Kp * err + Kd * delta(err) + Ki * sum(err) =20
<BR> * where Kp =3D proportional, Kd =3D derivative =
constant,=20
Ki =3D integral <BR>constant <BR> * =
Kp,Kd,Ki=20
can be changed with the hidden parameter _mts_load_constants =20
<BR> * in order to tune the system as desired. =20
<BR> This values should only be changed after =
gathering enough=20
information to <BR> determine that the mts is =
not=20
optimal. <BR> <BR>27. _mts_fastpath =
<BR> /*=20
hidden init.ora to enable dispatcher fastpath */ =
<BR> =20
default is false <BR> * Return TRUE if =
the system=20
should implement the dispatcher network =
<BR> *=20
fastpath. When enabled, the dispatcher fastpath causes network =
i/o =20
<BR> * to be buffered and only flushed when =
absolutely=20
necessary. When not <BR> * enabled, =
flushes=20
will occur for every dirty virtual circuit buffer. =
<BR> =20
<BR> <BR>*** The following parameters are from the Kernel SQL =
Library=20
manager <BR> <BR>28.=20
_kgl_multi_instance_lock <BR> Only =
for=20
debugging. all the _kgl_multi_instance_xxxx =20
<BR> "whether KGL to support multi-instance =
locks" =20
<BR> Default is 0 <BR> <BR>29.=20
_kgl_multi_instance_pin <BR> "whether KGL to =
support=20
multi-instance pins" <BR> Default is 0. =20
<BR> <BR>30. _kgl_multi_instance_invalidation =20
<BR> "whether KGL to support multi-instance=20
invalidations" <BR> Default is 0. =20
<BR> <BR>31. =
_row_cache_instance_locks =20
<BR> Kernel SQL Row cache management component, =
number of row=20
cache instance <BR> locks =20
<BR> default is 100 <BR> <BR>32.=20
_row_cache_buffer_size <BR> "size =
of row=20
cache circular buffer" <BR> default is =
200 =20
<BR> <BR>33. _messages <BR> " =
message queue=20
resources - dependent on # processes " <BR> The =
asynchronous=20
message mechanism allows processes to =
send =20
<BR> messages to each other. A =
process may=20
send a message to a <BR> specified=20
other process (always without waiting for a =
reply), =20
<BR> may wait for a message to arrive on its queue, =
and may=20
obtain <BR> the next message. =
Messages=20
sent to detached processes are =20
<BR> reliably delivered. Messages sent to foreground =
processes=20
are <BR> reliably delivered =
as =20
long as the process is active. The =20
<BR> mechanism also permits sending of a simple "reply", =
which is=20
a <BR> one-byte message without =20
queuing. It should normally be used =
<BR> =20
to reply to asynchronous messages, and =
this =20
is a safer <BR> =
technique than=20
regular messages for responding to foreground =20
<BR> processes. This mechanism is not used in =
single=20
process mode. <BR> <BR>34.=20
_cpu_count <BR> ksb - Kernel =
Service=20
Background processes <BR> "number of cpu's for =
this=20
instance" <BR> CPU_COUNT has to be set on some =
platforms=20
in order for Oracle to take <BR> =
advantage of=20
multi-processor system, on others it does not have effect =
on =20
<BR> performance since load balancing between =
processors is=20
handled by the o/s. <BR> <BR>35.=20
_debug_sga <BR> /* Debug SGA, =
don't=20
make the SGA a global section so we can set <BR>watchpoints =
<BR> <BR>36. _enqueue_locks =20 <BR> ksq1 - Kernal Service enQueues (1) =20 <BR> Definitions for enqueues client objects, "locks =for=20
<BR> - Processes =
begin=20
logging events using the current enabled events =20
<BR> - "OFF" =20
<BR> - Processes =
stop=20
tracing =
<BR> -=20
"ENABLE" <event_string> =20
<BR> - Add in the =
events=20
indicated in <event_string> to those which are =20
<BR> =
being=20
traced. <BR> =
-=20
"DISABLE" <event_string> =20
<BR> - No longer =
trace=20
events specified by <event_string> =20
<BR> = <BR>39._trace_buffers_per_process =20 <BR> Note that by default, tracing is NOT =enabled. In=20
<BR> These parameters are only there for debugging =
purposes.=20
Customers <BR> or support will never have to =
use=20
them. <BR> <BR>41. _trace_archive_start =20
<BR> "start trace process on SGA =
initialization" =20
<BR> <BR>42. _trace_flushing =20
<BR> "TRWR should try to keep tracing buffers =
clean" =20
<BR> <BR>43. _trace_enabled =
<BR> By=20
default, tracing is NOT enabled. In order to enable =
tracing, =20
<BR> _trace_enabled =3D true = <BR> =20 <BR>44. _trace_events <BR> If you =wish to=20
'_trace_events =3D "WAT,ALL"' to init.ora or execute =20
<BR> 'alter tracing enable "WAT,ALL"' in a sqldba=20
session. <BR> If you wish to limit tracing to =
specific=20
events, you can use the <BR> the following =
syntax: =20
<BR> alter tracing enable = "WAT,<id>,<id>..." =20 <BR> where "id" is either a specific event number, or =an event=20
<BR> <BR>45. _trace_archive_dest =20 <BR> "trace archival destination" = <BR> =20 <BR>46. _trace_file_size <BR> ="trace file=20
<BR> "VMS process priority to give to background=20 processes" <BR> default is 4 =20 <BR> <BR>55.=20
alert.log or not. Turned <BR> off in=20
benchmarks. <BR> <BR>57.=20
_large_memory_system : <BR> =
Used in=20
internal benchmarks. Doesn't concern us. <BR> =
"Configure=20
system to use memory and save cpu cycles, paging, etc =20
<BR> default is false <BR> <BR>58.=20
_wakeup_timeout <BR> This is WMONs sleeptime between =
checks of=20
it's queue of processes to wake. <BR> <BR>59.=20
_latch_wait_posting <BR> enable posting of processes =
that may=20
be waiting for a latch after a process <BR> =
<BR> =20
frees the same latch (set this parameter to a value greater than =
one =20
<BR> this parameter to a value greater than one for it to =
take=20
effect). <BR> <BR>60. _sql_connect_capability_code =20
<BR> allows database links from a pre-7.0.15 release to =
work with=20
release 7.1. <BR> It is necessary to set this =
parameter for=20
database links from a V6 ? </SPAN></FONT></DIV>
<DIV> </DIV>
<DIV><FONT color=3D#0000ff face=3D"Courier New" size=3D2><SPAN=20
class=3D138432314-09052000></SPAN></FONT> </DIV>
<P><B><FONT color=3D#0000ff face=3D"Comic Sans MS">Brian P. Mac =
Lean</FONT></B>=20
<BR><FONT color=3D#808080 face=3D"Comic Sans MS" size=3D1>Senior Oracle =
Database=20
Administrator</FONT> <BR><FONT color=3D#808080 face=3D"Comic Sans MS"=20
size=3D1>OCPv8/Oracle Master</FONT> <BR><FONT color=3D#808080 = face=3D"Comic Sans MS"=20 size=3D1>HomeBid.Com</FONT> <BR><FONT color=3D#808080 face=3D"Comic =Sans MS"=20
PM<BR><B>To:</B> Multiple recipients of list =
ORACLE-L<BR><B>Subject:</B> Re:=20
REF : _* initialization parameters (to all who have=20
replied)<BR><BR></DIV></FONT>
<DIV><FONT color=3D#000000 size=3D2>Some info you can find in Oracle =
Press, Oracle=20
Performance Tuning, Tips&Techniques by Richard =
Niemiec.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV> <DIV><FONT color=3D#000000 size=3D2>Djordje </FONT></DIV> <BLOCKQUOTE=20
<DIV><FONT face=3DArial size=3D2><B>-----Original = Message-----</B><BR><B>From:=20
</B>Benhayoune khalid <<A=20
=
href=3D"mailto:benhayoune_at_maroclear.co.ma">benhayoune_at_maroclear.co.ma</A=
>><BR><B>To:=20
</B>Multiple recipients of list ORACLE-L <<A=20 Received on Tue May 09 2000 - 09:44:58 CDT
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