sys_attrs_advfs(5) File Formats Manual sys_attrs_advfs(5)
NAME
sys_attrs_advfs - advfs subsystem attributes
DESCRIPTION
This reference page lists and describes attributes for the Advanced File System (advfs) kernel subsystem. Refer to the sys_attrs(5) refer-
ence 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; however, the values of the AdvfsMinFreeAc-
cessPercent and AdvfsMaxFreeAccessPercent attributes control allocation and deallocation of access structures. If AdvFS cannot allo-
cate any more access structures because of the memory limit imposed by AdvfsAccessMaxPercent, AdvFS posts an event and writes a mes-
sage in the following form to the console:
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 value. The percentage of system memory that is allocated to the AdvFS buffer cache, which stores file data.
Default value: 7 (percent)
Minimum value: 1 (percent)
Maximum value: 30 (percent)
Increasing this percentage can help improve disk I/O only if there is high reuse of cached data by your application workload.
Decreasing this percentage can improve performance if your application workload does not reuse AdvFS data or if your system has more
than 2 GB of memory. 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. Do not call live_dump() for a domain panic in either an unmounted or mounted domain.
Call live_dump() only if the domain panic occurred in a domain that is mounted. Call live_dump() if a domain panic occurred in
either a mounted or unmounted domain. Promote the domain panic to a system panic. This causes the system to crash, which yields a
crash dump when the system is rebooted. The value that controls the priority for moving synchronous or asynchronous 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 the queue.
Default value: 24 (requests)
Minimum value: 0 (requests)
Maximum value: 65536 (requests)
The default value should be appropriate for most configurations. However, 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 system call.
Default value: 1
SEE ALSO
sys_attrs(5)
AdvFS Administration
System Configuration and Tuning
sys_attrs_advfs(5)