NOTE:
For some filesystems the system
allocates inodes dynamically, based on system demand.
Generic filesystem parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
DNLCSIZE
1400/3800/13400
200
40000/160000/640000
KVM
FDFLUSHR
1
1
1200
FIFOBLKSIZE
16384
5120
65536
FLCKREC
300
100
2000
NAUTOUP
60
0
1200
NC_HASH_SIZE
0
0
8388608
ROOTFSTYPE
""
RSTCHOWN
0
0
1
SENDV_FORCE_RCOPY
1
0
1
DNLCSIZE
Defines the size of the directory name lookup cache (DNLC).
Generally, larger memory systems both support a heavier work load
and have more memory to spare, so the DNLCSIZE
tunable is automatically adjusted to be larger when more memory is present.
You can override the autotuned value by using idtune.
FDFLUSHR
Specifies the time interval, in seconds, for checking the need to write
the buffer caches and filesystem pages to disk.
FIFOBLKSIZE
FIFO block size.
The capacity of a pipe is 2*FIFOBLKSIZE
to allow a writer to send two messages before blocking on flow control.
FLCKREC
This parameter controls the number of record locking
structures used by the system.
NAUTOUP
Specifies the time, in seconds, for automatic filesystem updates
(for both the buffer cache and filesystem pages).
A system buffer is written to the hard disk when it has
been memory-resident for the interval specified by the
NAUTOUP parameter.
Specifying a smaller limit increases system reliability
(by writing the buffer caches and filesystem pages
to disk more frequently) and decreases system performance.
Specifying a larger limit increases
system performance at the expense of reliability.
NC_HASH_SIZE
Specifies the number of hash buckets
used for lookup in the directory name lookup cache.
The default value of 0 sets the number of hash lists to 1/4 the number of
``dnlc'' entries.
ROOTFSTYPE
Default root filesystem type.
RSTCHOWN
Specifies restricted file ownership changes flag.
Only ``0'' and ``1'' are valid values for RSTCHOWN.
A value of ``0'' is the Release 3 compatibility mode.
The owner of a file can change the user ID and group ID
of the file to any value, including non-existent user IDs
and group IDs.
When set to ``1'', RSTCHOWN
specifies the FIPS/BSD compatibility mode.
This restricts the ability to change ownership of a file.
Only the user with appropriate privilege or
root processes (those whose UID is ``0'') can change
the ownership of a file.
The owner of the file can change only the group ID of the file
to one group in which the owner has membership.
See
getgroups(2).
A user with appropriate privilege and root processes
can change the group ID of any file to any value.
SENDV_FORCE_RCOPY
When set to ``1'', the default, SENDV_FORCE_RCOPY
causes the
sendv(2)
system call to copy the data from the filesystem page into a streams buffer.
When set to ``0'', the filesystem page is locked down, and then used
``in place'' by the output stream; there is no copy.
When the stream is done with the data, the page is unlocked.
This mode of operation represents an optimization over the force copy mode.
However, if the stream were to exhibit a ``memory leak'' in the
optimized mode, then it is possible that the file page will stay
locked indefinitely.
This can cause a process to hang when it accesses the affected file,
or possibly even when it accesses the affected filesystem.
Buffer cache parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
BUFHWM
4096/16384/65536
10
16384/65536/262144
KVM
NBUF
256
20
3000
NHBUF
64
32
1024
NPBUF
64
20
100
NPGOUTBUF
16
1
100
BUFHWM
The amount of memory that can be used by
the transfer of filesystem structure data such as
inodes, indirect blocks, and cylinder groups.
It is not file data, which goes through virtual memory (VM) as pages.
NOTE:
In some other UNIX systems such as UNIX System V Release 3.2 and earlier,
the buffer cache was used for practically all disk I/O,
including the contents of files (that is, reads and writes).
The use of buffer cache changed with the introduction of virtual
memory (VM) and, therefore, changed the appropriate
tuning of BUFHWM.
Setting BUFHWM too low causes excess filesystem activity
to flush the buffer before it can be re-used.
Setting BUFHWM too high reduces the page pool size
and can increase paging.
In general terms, BUFHWM should grow proportionately with memory size.
The value of BUFHWM is autotuned and it should not have to be retuned.
However, you may want to retune BUFHWM for a specific condition;
for example, to reduce the value of BUFHWM
so there is more memory for use by X-windows.
Check sar -b before and after the change to ensure
that the %rcache and %wcache have not changed dramatically.
NBUF
Buffer cache I/O uses both buffers and buffer headers.
(See BUFHWM.)
Whenever a buffer header is needed, but none is available,
the system dynamically allocates more buffer
headers in chunks of NBUF headers at a time.
There is no limit to the number of
buffer headers in the system, but the tunable BUFHWM
limits the number of kilobytes that can be used by buffers
and, therefore, effectively limits
the number of buffer headers that are allocated.
Once allocated, buffer header space cannot be freed for other uses.
Therefore, take care when you raise the value of NBUF.
A higher value of NBUF decreases the number of times
the Kernel Memory Allocator must be called to allocate space for buffer
headers, but this also can result in the allocation of headers that are
not used.
NHBUF
Specifies the size of the hash table used to locate a buffer,
given a device number and a block number.
The value must be a power of ``2'' from ``32'' to
``1024'', inclusive.
This value should be about one quarter of the total buffers available.
A value between 1/8 and 1/4 of BUFHWM is typically sufficient.
NPBUF
Specifies the number of physical I/O buffers to allocate;
one is needed for each active physical read or write.
There is no rule for adjusting NPBUF.
However, if you expect a lot of I/O and filesystem activity,
improvement may be gained by raising NPBUF.
NPGOUTBUF
Specifies the number of buffer headers reserved for the pageout
daemon to avoid deadlock.
CDFS filesystem parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
CDFSNINODE
2048
150
20000
KVM
CDFSNINODE
Specifies the maximum number of inode entries in the CDFS
inode table when a CDFS file is configured in your system.
DOSFS filesystem parameters
Parameter
Dflt
Min
Max
DOSFSFLUSH
60
1
120
DOSFSNINODE
200
1
400
DOSFSFLUSH
Specifies how often to run the fsflush daemon
to write data out to disk on DOSFS filesystems.
A smaller value causes the daemon to run more often,
making the filesystem ``harder,'' that is,
less likely to lose data in a crash.
However, it does take some CPU time.
DOSFSNINODE
Specifies the maximum number of inode entries in the DOSFS
inode table when a DOSFS file is configured in your system.
MEMFS filesystem parameters
Parameter
Dflt
Min
Max
MEMFS_MAXKMEM
524288
65536
4096000
MEMFS_MAXKMEM
Specifies the allocatable kernel memory in bytes for memfs.
NAMEFS filesystem parameters
Parameter
Dflt
Min
Max
NAMEFSFLUSH
60
1
120
NAMEFSFLUSH
Specifies the flush time interval for namefs.
NFS filesystem parameters
Parameter
Dflt
Min
Max
FIRSTRETRY
1
1
5
KEYNRETRY
6
1
10
KEYTIMEOUT
30
5
50
MAXDUPREQS
400
200
8000
NFS_ASYNC_MAX
8
0
40
NFS_ASYNC_TIMEOUT
4
0
10
NFS_MAXCLIENTS
6
0
20
NFS_MMAP_TIMEOUT
30
30
180
NFS_NRA
1
0
1
NFS_NUM_MOUNTS
256
256
1024
NFS_RETRIES
5
1
10
NFS_TIMEO
10
4
15
NFSD_MAX
8
4
128
NFSD_MIN
2
1
32
NFSD_TIMEOUT
8
3
10
NRNODE
300
100
1300
RECVRETRIES
2
1
10
RTIMETIMEOUT
5
2
15
WORKTIMEOUT
3
3
7
FIRSTRETRY
Specifies the number of times to retry contacting the local lock manager
before failing.
KEYNRETRY
Specifies the number of times to retry contacting the keyserver
before failing.
KEYTIMEOUT
Specifies the maximum time, in seconds, to wait for the keyserver
to reply to a request.
MAXDUPREQS
Specifies the maximum number of cached items
in the server side duplicate request cache.
Adjust MAXDUPREQS to the service load so that
a response entry is likely when the first retransmission is received.
NFS_ASYNC_MAX
Specifies the maximum number of lightweight processes (LWPs)
that can be created for asynchronous I/O over NFS.
NFS_ASYNC_TIMEOUT
Specifies, in seconds,
the time-to-live of the lightweight processes (LWPs)
that do asynchronous I/O over NFS.
If an asynchronous request is not generated in the system in
NFS_ASYNC_TIMEOUT seconds, the LWPs exit.
NFS_MAXCLIENTS
Specifies the number of active RPC client handles that NFS can cache.
Increase this number only when more memory is added to the system.
NFS_MMAP_TIMEOUT
Specifies, in seconds,
the interval between the time the NFS mmap
lightweight processes (LWP)
wakes up and updates file attributes for all mmaped files.
Given the large amount of CPU time the mmap
LWP can potentially
consume, in cases where a significant number of files have been
mmaped over NFS, this value should not be made too small.
NFS_NRA
Specifies the number of pages to read ahead for each read operation,
if possible.
Read-ahead over NFS can be turned off by changing this
value to ``0''.
NFS_NUM_MOUNTS
Specifies the maximum number of mounts allowed on the client system.
NFS_RETRIES
Specifies the maximum number of NFS retries before failing the
NFS operation for a soft mount.
Typically, the default value should not be changed.
NFS_TIMEO
Specifies, in seconds, the maximum initial time to wait for an NFS
server to respond to a client request.
On machines connected to networks where packets tend to get lost,
this value should be changed.
On some of these networks you will have greater success
getting the packet if you retry after a minimum wait;
on other networks, you will have greater success if you wait longer.
NFSD_MAX
Specifies the maximum number of lightweight processes (LWPs)
that can be created for servicing NFS requests from clients.
You may want to increase this value for dedicated NFS servers.
NFSD_MIN
Specifies the minimum number of lightweight processes (LWPs)
that should always exist in the system for servicing NFS requests
from NFS clients.
You may want to increase this value for dedicated NFS servers.
NFSD_TIMEOUT
Specifies, in seconds,
the time-to-live of the lightweight processes (LWPs)
that service NFS requests from clients.
If the LWP is idle for more than
NFSD_TIMEOUT seconds
and there are more than NFSD_MIN LWPs,
the LWPs exit.
NRNODE
Specifies the maximum number of rnode structures
to be allocated for NFS.
An rnode is a node specific to the NFSfilesystem type.
RECVRETRIES
Specifies the number of times to retry an RPC call for the client
side.
RTIMETIMEOUT
Specifies the maximum time, in seconds, to wait for a reply
to a request for synchronization with the server.
WORKTIMEOUT
Specifies the maximum time, in seconds, to wait for
the local manager to reply to a request.
SFS filesystem parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
SFSFLUSH
60
1
120
SFSINODELWM
50
1
1000
SFSNINODE
8000/32000/128000
150
40000/160000/640000
KVM
SFSTIMELAG
10000
0
1000000
SFSFLUSH
Specifies how often the fsflush daemon
writes sfs inode data out to disk on sfS filesystems.
A smaller value causes the daemon to write more often,
making the filesystem ``harder,'' that is,
less likely to lose data in a crash.
However, it does take some CPU time.
SFSINODELWM
Specifies the minimum number of inodes to keep in the dynamically
allocated inode pool.
This keeps the system from returning space to the KMA (Kernel Memory
Allocator) when it is likely to need it back in the inode pool
relatively quickly.
SFSNINODE
Specifies the maximum number of inode entries in the sfs inode table.
It's important when an sfs file is configured in your system.
An sfs inode is a data structure
that typically describes a file, directory,
link and named pipe in an sfs filesystem type.
Too few incore inodes cause:
a poor buffer cache read/hit ratio (obtained with sar -b)
a higher number of inodes with pages recycled
a poor page attach rate (obtained with sar -p)
This tunable is automatically adjusted based on memory size,
but you can override the autotuned value by using
idtune(1M).
SFSTIMELAG
A heuristic to not reuse inodes sooner than the specified number of ticks,
if possible.
S5 filesystem parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
S5FSFLUSH
60
1
120
S5INODELWM
50
1
1000
S5NINODE
4000
150
20000
KVM
S5FSFLUSH
Specifies how often the fsflush daemon
writes s5 inode data out to disk on s5 filesystems.
A smaller value causes the daemon to write more often,
making the filesystem ``harder,'' that is,
less likely to lose data in a crash.
However, it does take some CPU time.
S5INODELWM
Specifies the minimum number of inodes to keep in the dynamically
allocated inode pool, also known as the low water mark (LWM).
This keeps the system from returning space to the KMA (Kernel Memory
Allocator) when it is likely to need it back in the inode pool
relatively quickly.
S5NINODE
Specifies the maximum number of inode entries
in the memory-resident s5 inode table.
This parameter is important
when an s5 filesystem type is configured into your system.
An s5 inode is a data structure
that typically describes a file, directory,
link and named pipe in an s5 filesystem type.
Too few incore inodes causes:
a poor buffer cache read/hit ratio (obtained with sar -b)
a higher number of inodes with pages recycled
a poor page attach rate (obtained with sar -p)
This tunable is automatically adjusted based on memory size,
but you can override the autotuned value by using idtune.
UFS filesystem parameters
Parameter
Dflt
Min
Max
NDQUOT
200
100
400
NDQUOT
The size of the kernel quota table for the ufs filesystem.
There is one entry for each user.
Therefore, NDQUOT should be more than the maximum number of users
that can be logged onto the system if a
ufs or sfs filesystem type is being used.
If quotas are in effect, the table entries limit the amount of
disk space a user can use.
If there are no available entries, the message:
dquot table full
is displayed on the console.
If this occurs, increase the value of NDQUOT.
VXFS filesystem parameters
Parameter
Dflt 64/256/1024
Min
Max 64/256/1024
Auto
VXFSNINODE
7000/16000/64000
150
28000/48000/128000
KVM
VXFSNINODE
Specifies the maximum number of inode entries in the vxfs inode table.
It's important when a vxfs filesystem is configured in your system.
A vxfs inode is a data structure
that typically describes a file, directory,
link and named pipe in a vxfs filesystem type.
Too few incore inodes causes:
a poor buffer cache read/hit ratio (obtained with sar -b)
a higher number of inodes with pages recycled
a poor page attach rate (obtained with sar -p)
This tunable is automatically adjusted based on memory size,
but you can override the autotuned value by using
idtune(1M).
NOTE:VXFSNINODE is the only vxfs tunable parameter that can
be tuned using idtune, but there are a number of other
vxfs tunable I/O parameters that can be tuned using the
vxtunefs command.
See
vxtunefs(1M).