LOGGING
CLEANERS*
 |
1 per
disk if < 20 disks |
|
1 per
2 disks if 20 to 100 |
|
4 per
disk if > 100 |
|
UPDATE
at least one per LRU queue pair. This has
most recently been best for me. |
|
If
–f indicates that all cleaners are active allocate more. |
PHYSDBS
|
!
rootdbs. Place on a separate spindle |
PHYSFILE
|
= usrthreads
* 5 (or size of most freq. blob) * 4 |
PHYSBUFF
|
= usrthrds
* 5 * 4 |
|
UNLESS
tblspace blobs in DB w/o logging then usrthrds * size of freq blob
pg * 4 |
LOGFILES
|
>
3 |
|
In
all my manuals I can find no good reference for performance tuning
this parameter. |
|
I
have no experience adjusting this save for eliminating anomalous behavior. |
LOGSIZE
|
>
200kb |
|
small
for greatest recovery, if tape slow, or blobpages volatile |
|
(connects
* maxrows (in one trans)) * 512 |
LOGBUFF
|
size
of 3 LL buffers in RAM |
|
determines
freq of flushing to disk |
LOGSMAX
|
LOGFILES
+ 3 |
CKPTINTVL
|
adjust
interval of checkpoints, see LRU. |
|
For
data loading (except HPL express mode) and parallel index builds 3000 |
|
a large
interval will allow size of physlog (i.e. amount of work accomplished)
to determine when chkpts occure. |
|
–F
will show if writes are LRU driven or CHKPTINTVL driven |
|
–l
and –m will determine if checkpoint interval is driven by Physlog
= 75% full or this param |
LRUS*
|
max(4,
NUMCPUVPS) |
|
if
-R shows #dirty pages > LRU_MAX add LRU Qs. If no change increase
CLEANERS |
|
UPDATE:
4 per CPUVP (this relationship has most recently
been best for me.) |
|
1 per
500-750 buffers, up to 128 (max) |
|
More
LRUs better support large number of users by reducing buffwaits |
To monitor –g
spi shows contention for individual LRU queues
LRU_MAX[MIN]_DIRTY
- %buffers assigned to modified queue
|
lower
to decrease checkpoint duration |
|
For
data loading (except HPL express mode) & parallel index builds
70 & 80%, allow to almost fill before flushing |
Monitor: –R queue
length, -F writes forced by this parameter by CLEANER thread
LTAPEDEV
|
Set
to /dev/null Informix will just marked the LL as backed up, not even
going through the motions. This should be done only on systems where
logical log recovery is not required and the user has been made aware
of the implications. |
LTXHWM
|
50 |
LTXEHWM
|
60 |
LBU_PRESERVE
- Preserve last log for log backup
NOTES:
|
If
physlog frequently fills decrease CKPINTVL |
|
phys
logging - buffsize/pages IO SB >75%, if near 100% increase physbuff
size |
|
physical
and logical log buffers should be about 75% full when flushed. |
|
Huge
bang for the buck makes Checkpoints another early thing to look at. |
|
|
Introduction
Main &
CPU
Disk IO
Logging
Memory
& DSS
Miscellaneous
Notes
Print
Version
bamph
|
