MAXAIO导致Oracle启动hang问题(二)
ersions believed to be affected Versions >= 10.2.0.4 but BELOW 11.1
Versions confirmed as being affected
10.2.0.5
Platforms affected
Linux X86-64bit
Linux 32bit
It is believed to be a regression in default behaviour thus:
Regression introduced in 10.2.0.5
Fixed:
This issue is fixed in
11.1.0.6 (Base Release)
10.2.0.5.2 Patch Set Update
10.2.0.5 Patch 5 on Windows Platforms
Symptoms:
Related To:
Hang (Process Spins)
Waits for "i/o slave wait"
DISK_ASYNCH_IO
Description
This problem is introduced in 10.2.0.5
It only affects platforms where Oracle has to reserve async IO slots,
such as Linux platforms.
If the OS async IO layer is underconfigured and an Oracle process
cannot get sufficient AIO slots then rather than reverting to
using non AIO call the process may go into an infinite spin
under ksfdrwat0.
Rediscovery notes:
The spin will be preceded by messages in the trace
file of the form:
WARNING:io_submit failed due to kernel limitations MAXAIO
for process=0 pending aio=0
WARNING:asynch I/O kernel limits is set at AIO-MAX-NR=65536 AIO-NR=65518
WARNING:1 Oracle process running out of OS kernelI/O resources aiolimit=0
Notice specifically that the value for aiolimit is reported as "0"
for this bug.
The process then spins in ksfdrwat0 typically with a stack showing
skgfqio ()
ksfdgo ()
ksfdwtio ()
ksfdwat1 ()
ksfdrwat0 () <<< Spin point
ksfdblock ()
kcflwi ()
kcflci ()
kcblci ()
kcblcio ()
kcblgt ()
kcbldrget ()
It will show repeated waits for "i/o slave wait", which can be
misleading as that is normally considered an idle wait event.
Workaround
Raise the OS AIO limits such that the number of concurrent slot
requirements never exceeds the OS limit.
ie: Increase AIO-MAX-NR
OR
Disable async IO (Set DISK_ASYNCH_IO=FALSE)
See Note:1313555.1 for additional notes on this issue.
Please note: The above is a summary description only. Actual symptoms can vary. Matching to any symptoms here does not confirm that you are encountering this problem. For questions about this bug please consult Oracle Support.
References
Bug:9949948 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article