sys_attrs_advfs - advfs subsystem attributes
This reference page lists and describes attributes for the Advanced File
System (advfs) kernel subsystem. Refer to the sys_attrs(5) reference page
for an introduction to the topic of kernel subsystem attributes.
An asterisk (*) preceding the name of an attribute in the following list
means that the attribute can be configured at run time. Values of other
attributes cannot be changed without rebooting the system.
The maximum percentage of the malloc pool (pageable memory) that can be
possibly be allocated for AdvFS access structures.
Default value: 25 (percent)
Minimum value: 5 (percent)
Maximum value: 95 (percent)
AdvfsAccessMaxPercent is a high-water mark of possible memory use for
access structures. If AdvFS cannot allocate any more access structures
because of the memory limit imposed by AdvfsAccessMaxPercent, AdvFS
posts an event and writes a message in the following form to the con-
Could not create new AdvFS access structure;
already at AdvFS memory limit as specified by
AdvfsAccessMaxPercent value of percent.
At this point, the system administrator can either kill processes to
cause files to be closed or set AdvfsAccessMaxPercent to a higher
One of the following four values that control what AdvFS does in the
event of a domain panic. The live_dump() function mentioned in these
descriptions is a system call used only inside the kernel. This system
call creates vmunix and vmcore files in the /var/adm/crash directory.
In other words, values that enable the live_dump() call allow the
creation of dump files without calling panic() to crash the system.
0 Do not call live_dump() for a domain panic in either an
unmounted or mounted domain.
1 (the default)
Call live_dump() only if the domain panic occurred in a domain
that is mounted.
2 Call live_dump() if a domain panic occurred in either a mounted
or unmounted domain.
3 Promote the domain panic to a system panic. This causes the
system to crash, which yields a crash dump when the system is
The value that controls the priority for moving synchronous or asyn-
chronous I/O requests from the consolidation queue to the device queue.
When the value is 1, AdvFS first flushes synchronous I/O to disk. When
the value is 0 (zero), asynchronous I/O is flushed to disk, regardless
of synchronous I/O.
Default value: 1
Do not modify the default setting for this attribute unless instructed
to do so by support personnel or by patch kit documentation.
The highest number of I/O requests that can be on the AdvFS device
queue before that queue is limited to synchronous requests. The AdvFS
device queue accepts both asynchronous I/O requests and synchronous I/O
requests. When the number of requests on the device queue exceeds the
value of this attribute, only synchronous requests are accepted onto
Default value: 24 (requests)
Minimum value: 0 (requests)
Maximum value: 65536 (requests)
The default value should be appropriate for most configurations. How-
ever, you may need to modify the default value for systems with very
fast or very slow devices and adapters. One guideline is to specify a
value for the AdvfsMaxDevQLen attribute that is less than or equal to
the average number of I/O operations that can be performed in 0.5
seconds. If you do not want to limit the size of the device queue, set
the value of the AdvfsMaxDevQLen parameter to 0 (zero).
The threshold number of fragment groups on the free list that starts
fragment group deallocation from the list. Deallocation starts when the
number of fragment groups on the free list is higher than this value.
Default value: 48 (groups)
Minimum value: 4 (groups)
Maximum value: 8,388,608 (groups)
The threshold number of fragment groups on the free list that stops
fragment group deallocation from the list. Deallocation stops when the
number of fragment groups on the free list is less than this value.
Default value: 16 (groups)
Minimum value: 3 (groups)
Maximum value: 8,388,607 (groups)
The number of 512-byte blocks that can be on the readylazy queue before
AdvFS starts moving I/O requests to the device queue.
Default value: 16 K (blocks)
Minimum value: 0, which disables buffering on the readylazy queue
Maximum value: 32 K (blocks)
A value that controls whether modified (dirty) mmapped pages are
flushed to disk during a sync() system call. If the value is 1, the
dirty mmapped pages are asynchronously written to disk. If the value
is 0 (zero), dirty mmapped pages are not written to disk during a sync
Default value: 1
System Configuration and Tuning