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Sun QFS and Sun Storage Archive Manager 5.3 Reference Manual Sun QFS and Sun Storage Archive Manager 5.3 Information Library |
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Sun QFS and Sun Storage Archive Manager 5.3 Reference Manual Sun QFS and Sun Storage Archive Manager 5.3 Information Library |
1. User Commands (Man Pages Section 1)
2. Maintenance Commands (Man Pages Section 1M)
3. Library Functions (Man Pages Section 3)
4. Library Functions (Man Pages Section 3X)
5. File Formats (Man Pages Section 4)
NAME
mount_samfs - Mounts a Sun QFS or SAM-QFS file system
SYNOPSIS
mount -F samfs [generic_options]
[-o FSType_specific_options] special | mount_point
mount -F samfs [generic_options]
[-o FSType_specific_options] special mount_point
AVAILABILITY
SUNWsamfs
DESCRIPTION
The mount command attaches a file system to the file system
hierarchy at the specified mount_point, which is the path
name of a directory. This man page describes how to mount a
Sun QFS or SAM-QFS file system, and it explains the unique
options that can be used when mounting these file systems.
If the first form of the command is used, which specifies
either a special or a mount_point but not both, the mount
command searches the /etc/vfstab file and fills in missing
arguments, including the FSType_specific_options. The
mount(1M) command also searches the
/etc/opt/SUNWsamfs/samfs.cmd file for mount options.
For more information on the mount(1M) command, see the
mount(1M) man page. For more information on the
/etc/opt/SUNWsamfs/samfs.cmd file, see the samfs.cmd(4) man
page.
OPTIONS
-F samfs Specifies that the file system being mounted is of
type samfs. This is a required option if you are
mounting a Sun QFS or a SAM-QFS file system.
These file systems are all type samfs.
generic_options
One or more generic Solaris file system options.
For a list of possible generic_options, see the
mount(1M) man page.
-o FSType_specific_options
A list of mount options specific to file systems
of type samfs. If specifying multiple options,
separate each option with a comma and no
intervening spaces. For the list of possible
-o FSType_specific_options, see one or more of the
following headings on this man page:
o Miscellaneous Tuning Options
o I/O Options
o Storage and Archive Management Options
o Shared File System Options
o Multireader File System Options
o Sun QFS and SAM-QFS Options
If no FSType_specific_options are specified, the
the file system is mounted as a read/write file
system.
If invalid options are specified, a warning
message is generated and the invalid options are
disregarded.
NOTE: If running the Sun QFS software on a Linux
client, the available mount options are very
limited. The following mount options are the ONLY
ones available on a Linux client system: rw, ro,
retry, shared, rdlease, wrlease, aplease,
minallocsz, maxallocsz, min_pool, meta_timeo,
noauto, and auto.
The noauto and auto options are only recognized
within the /etc/fstab file and min_pool only in
the samfs.cmd file. The maximum value for
meta_timeo is 60.
special The Family Set Name from the Sun QFS
or SAM-QFS master configuration file (mcf). For
more information on this file, see the mcf(4) man
page.
mount_point
The path name or directory at which the file
system is to be mounted. If the mount_point has
any contents prior to the mount operation, these
are hidden until the file system is unmounted.
MISCELLANEOUS OPTIONS
The following options can be used when mounting a Sun QFS or
SAM-QFS file system. These options can affect file system
features and system performance.
nosam | sam
The nosam option mounts a SAM-QFS file system, but
only the file system functionality is enabled.
The archiving, releasing, and staging
functionality is disabled. When a file system is
mounted with this option, the file system returns
ENOSPC when it reaches 100% capacity.
Note that mounting a file system with the nosam
option offers no data protection for newly created
files or for previously archived files that have
been modified. The default is sam.
noarscan | arscan
The noarscan option disables file system scans,
typically performed by the sam-arfind daemon, for
finding archive candidates on a mounted file
system. This mount option can be useful for file
systems in which new files are no longer being
created yet staging and releasing are still
desired. The default is arscan.
nosuid Mounts the file system with setuid execution
disallowed. By default, the file system mounts
with setuid execution allowed.
nogfsid | gfsid
The nogfsid option disables the setting of a
global file system id, and uses the historical
setting of the root slice device type paired with
the file system type. The gfsid option enables
the setting of a global file system id, and uses
the file system id that is stored in the
superblock, which consists of the file system
creation time paired with the hostid. The default
is gfsid.
nocdevid | cdevid
The nocdevid option disables the setting of a
global file system device id, and uses the
historical setting of the root slice device type.
The cdevid option enables the setting of a global
file system device id that consists of the samioc
module major number paired with the file system
equipment number as specified in the mcf(4) file.
The default is cdevid.
notrace | trace
The notrace option disables file system tracing.
The trace option enables file system tracing. The
default is trace.
noquota | quota
The noquota option disables file system quotas.
The quota option enables file system quotas,
provided that at least one file system quota file
is present. The default is quota. For more
information on quotas, see the Sun QFS File System
Configuration and Administration
Guide.
sync_meta=n
Specifies whether or not the metadata is written
to the disk every time it changes, as follows:
o If sync_meta=0, metadata is held in a buffer
before being written to disk. This delayed
write delivers higher performance. This is the
default for Sun QFS and SAM-QFS file systems
that are not mounted as multireader file
systems or as Sun QFS shared file systems.
o If sync_meta=1, metadata is written to disk
every time it changes. This slows performance,
but it ensures data consistency. This is the
default for Sun QFS file systems that are
mounted as multireader file systems or as Sun
QFS shared file systems. In a Sun QFS shared
file system, this is the setting that must be
in effect if failover capability is required.
worm_capable
The worm_capable option allows Write Once Read
Many (WORM) files to be stored in SAM-QFS
filesystems. Enabling this feature allows the
WORM flag to be set on files and directories. Once
the WORM flag is set, a file's data and path are
immutable and the file can not be deleted until
its retention period expires. In addition, the
volume on which the WORM file resides can not be
deleted using sammkfs.
worm_lite The worm_lite option is similar to the
worm_capable mount option but eases the
restrictions regarding actions that can be taken
on WORM-enabled volumes and retained files. WORM
lite enabled volumes can be deleted using sammkfs.
Retained files can be removed before their
retention period expires and their retention
period can be shortened (must have root
privileges). File data and path remain immutable.
worm_emul The worm_emul option is similar to the
worm_capable mount option and enables WORM
"Emulation mode". The difference with this option
is the trigger used to retain files is the
transition from a writable to read-only file.
File data and path are immutable after appying the
WORM trigger. A file retained in this mode can
not be deleted until it's retention period
expires. Volumes containing WORM emulation mode
files can not be deleted using sammkfs.
emul_lite The emul_lite option is similar to the
worm_capable mount option and enables WORM
"Emulation Lite mode". The trigger to retain
files is the transition from a writable to read-
only file. Retained files can be removed before
their retention period expires and their retention
period can be shortened (must have root
privileges). Data and path changes to a file are
immutable after applying the trigger. Emulation
lite enabled volumes can be deleted using sammkfs.
def_retention=n
The def_retention option sets the default
retention period. This option requires a WORM
mount option enabled. This option sets the
default retention period for files which have the
WORM feature enabled with no supplied retention
period. The retention period can take three
forms. A value of permanent (or 0)specifies
permanent retention. A value of the form MyNdOhPm
where M, N, O, P are arbitrary non-negative
integers; y, d, h, m specify the number of years,
days, hours, and minute(s) respectively. Note
that combinations of this form are allowed, and
specifiers may be omitted, e.g., 5y, 3d1h, 4m.
The final form is a simple integer value in
minutes for n, an integer 1 < n < 2147483647 (231
- 1). If this option is not supplied, a 30 day
(43,200 minute) default retention period is used.
rd_ino_buf_size=n
rd_ino_buf_size sets the size of buffer to n. This
is the buffer which is used to read the .inodes
file into buffer cache. For n, specify an integer
such that 1024 < n < 16384. n is in units of
bytes and rounded down to the nearest power of 2.
The default is 16384 bytes.
wr_ino_buf_size=n
wr_ino_buf_size sets the size of the buffer to n.
This is the buffer which is used to synchronously
write an inode through to the disk. For n,
specify an integer such that 512 < n <
rd_ino_buf_size. n is in units of bytes and
rounded down to the nearest power of 2. The
default is 512 bytes.
BLOCK FILE SYSTEM GENERIC OPTIONS
The following options are available for Sun QFS and SAM-QFS
file systems. Also see the mcf(4) man page.
stripe=n Sets the stripe width for the block-based file
system to n disk allocation units (DAUs). The
stripe width means that n * DAU bytes are written
to one data device logical equipment number (LUN)
before switching to the next LUN. The DAU size is
set on the sammkfs(1M) command's -a option when
the file system is initialized. For n, specify an
integer such that 0 < n < 255. If n=0, files are
round robined on each slice.
The default n on file systems with an ms Equipment
Type and on file systems with an ma Equipment Type
with no striped group (gx) components is as
follows:
o 128 kilobytes/DAU for DAUs < 128 kilobytes
o 1 for DAUs > 128 kilobytes
By default, n=0 on a Sun QFS shared file system.
By default, n=0 on file systems with an ma
Equipment Type with any striped group (gXXX)
components.
NOTE: The system sets stripe=0 if mismatched
striped groups exist.
I/O OPTIONS
The following options are available for Sun QFS and SAM-QFS
file systems. They allow changing the type of I/O for a
file based on I/O size and history. Note that if direct I/O
is specified for a file, these options are ignored and all
I/O to regular files is direct, if possible. Well-aligned
I/O occurs when the file offset falls on a 512-byte boundary
and when the length of the I/O transfer is at least 512
bytes.
dio_rd_consec=n
Sets the number of consecutive I/O transfers with
a buffer size greater than the specified lower
limit (which is dio_rd_form_min for aligned reads
or dio_rd_ill_min for misaligned reads) to n
operations. By default, n=0, which means that no
default direct reads occur based on I/O sizes.
Also, by default, dio_rd_form_min and
dio_rd_ill_min are ignored.
dio_rd_form_min=n
Sets the read well-aligned lower limit to n 1024-
byte blocks. By default, n=256, 1024-byte blocks.
If n=0, automatic I/O type switching for well-
aligned reads is disabled.
dio_rd_ill_min=n
Sets the read misaligned lower limit to n 1024-
byte blocks. By default, n=0, which disables
automatic I/O type switching for misaligned reads.
dio_wr_consec=n
Sets the number of consecutive I/O transfers with
a buffer size above the specified lower limit
(which is dio_wr_form_min for aligned writes or
dio_wr_ill_min for misaligned writes) to n
operations. By default, n=0, which means that no
default direct writes occur based on I/O sizes.
Also, by default, dio_wr_form_min and
dio_wr_ill_min are ignored.
dio_wr_form_min=n
Sets the write well-aligned lower limit to n
1024-byte blocks. By default, n=256 1024-byte
blocks. Setting n=0 disables automatic I/O type
switching for well-aligned writes.
dio_wr_ill_min=n
Sets the write misaligned lower limit to n 1024-
byte blocks. By default, n=0, which disables
automatic I/O type switching for misaligned
writes.
atime= -1 | 0 | 1
The file system is mounted by default with cached
access time recording (atime = 0). This means
access time updates to disk are deferred for up to
1 minute after the file is last accesssed. Note,
the file access time is immediately updated on
disk if SAM is enabled and the space used is above
the low water mark or when the access time
coincides with updates to the ctime or mtime. See
stat(2). The access time is also updated when the
the file system is unmounted. If atime = 1, the
file system will always update access time on
disk. If atime = -1, the file system will not
update access time except when it coincides with
updates to the ctime or mtime. See stat(2). The
atime = -1 option reduces disk activity on file
systems where access times are unimportant (for
example, a Usenet news spool). Note, atime = -1,
should not be set when SAM is enabled.
The POSIX standard requires that access times be
marked on files. Note, for atime = 0 (the
default), the current access time may not be
updated on disk in case of an interruption.
noatime The noatime is added to be compatible with other
file systems. If noatime is specified, atime = -1
will be set. This means the file system will not
update access time except when it coincides with
updates to the ctime or mtime. See stat(2).
Note, noatime, should not be set when SAM is
enabled.
forcedirectio
Specifies direct I/O as the default I/O mode.
This means that data is transferred directly
between the user's buffer and disk. The
forcedirectio option should be specified only if
the file system is used for large block aligned
sequential I/O. For more information, see the
directio(3C), setfa(1), sam_setfa(3), and
sam_advise(3) man pages. The default I/O mode is
buffered (uses the page cache).
nodio_szero | dio_szero
The dio_szero option causes uninitialized areas of
sparse files written with direct I/O to be zeroed
when the area is accessed. This makes the sparse
file behavior the same as that for paged I/O. By
default, sparse files written by direct I/O do not
have the uninitialized areas zeroed for
performance reasons. The default is nodio_szero.
force_nfs_async
Causes the file system to cache nfs data written
to the server even if nfs has requested that the
data be written synchronously through to disk.
The force_nfs_async option is only useful if the
file system is mounted as a nfs server and the
clients have set the nfs mount option noac. The
default nfs noac behavior without force_nfs_async
causes data to be synchronously written through to
disk. Caution, the force_nfs_async option violates
the nfs protocol and should be used with care.
Data may be lost in the event of a server
interruption. Also, data is cached on the server
and will not be immediately seen by all the
clients if there are multiple nfs servers.
Multiple nfs servers can be enabled with Shared
QFS.
sw_raid Causes the file system to align the writebehind
buffer. This option should be set if the software
raid feature of packages such as Solstice
DiskSuite is being used on this file system. This
option is off by default.
readahead=n
Sets the maximum readahead value to n. The
readahead option specifies the maximum number of
bytes that can be read ahead by the file system.
n is in units of kilobytes and must be a multiple
of 8. For n, specify an integer such that 0 < n <
16777216. The default is 1024 (1,048,576 bytes).
writebehind=n
Sets the maximum writebehind value to n. The
writebehind option specifies the maximum number of
bytes that can be written behind by the file
system. n is in units of kilobytes and must be a
multiple of 8. For n, specify an integer such
that 8 < n < 16777216. The default is 512
(524,288 bytes).
flush_behind=n
Sets the maximum flush_behind value to n. When
enabled, modified pages that are being written
sequentially are written to disk asynchronously to
help the Solaris VM layer keep the pages clean.
This option sets the maximum flush_behind value to
n. n is in units of kilobytes. For n, specify an
integer such that 0 < n < 8192. The default is 0,
which disables flush behind.
wr_throttle=n
Sets the maximum number of outstanding write bytes
for one filesystem to n kilobytes. If n = 0,
there is no limit.
The default is 5% of system memory. Using the 5%
formula, and given the memory size on the left,
the wr_throttle setting is on the right:
1 GB 51 MB
4 GB 205 MB
16 GB 819 MB
64 GB 3.2 GB
qwrite Enables simultaneous reads and writes to the same
file from different threads. Specify this option
only if users of the file system handle multiple
simultaneous transactions to the same file. For
example, this is useful for database applications.
This option improves I/O performance by queuing
multiple requests at the drive level.
By default, qwrite is not enabled, and the file
system disables simultaneous reads and writes to
the same file. This is the mode defined by the
UNIX vnode interface standard that gives exclusive
access to only one writer and forces other writers
and readers to wait.
The qwrite option is disabled for NFS reads or
writes of the file system.
noabr | abr
For Oracle RAC with SAM-QFS AIO only. Disable
(enable) Application Based Recovery of software
mirrors. Applies only to SAM-QFS filesystems
built on Solaris Volume Manager mirrored volumes
that likewise support Application Based Recovery.
Default is enabled.
nodmr | dmr
For Oracle RAC with SAM-QFS AIO only. Disable
(enable) Directed Mirror Reads of software
mirrors. Applies only to SAM-QFS filesystems
built on Solaris Volume Manager mirrored volumes
that likewise support directed mirror reads.
Default is enabled.
STORAGE AND ARCHIVE MANAGEMENT OPTIONS
The following options can be used when mounting a SAM-QFS
file system. These options pertain to the storage and
archive management facilities of these file systems.
nosam_db | sam_db
The nosam_db option indicates there is no
associated database with this file system. The
sam_db option indicates there is an associated
database with this file system and file system
activity logging is enabled. The sam-fsd daemon
starts sam-fsalogd who logs file system activity.
For more information, see the fsalogd.cmd(4) man
page. The default is nosam_db.
high=n Sets the high-water mark for disk cache
utilization to n percent. When the amount of
space used on the disk cache reaches n percent,
the SAM-QFS file systems start the releaser
process. For more information, see the sam-
releaser(1M) man page. If n is set to 100,
releaser is not started and ENOSPC is returned.
The default is 80.
low=n Sets the low-water mark for disk cache utilization
to n percent. When the amount of space used on
the disk cache reaches n percent, the SAM-QFS file
system starts the releaser process, which stops
releasing disk space. The default is 70.
partial=n Sets the default partial release size for the file
system to n kilobytes. The partial release size
is used to determine how many bytes at the
beginning of a file marked for partial release
should be retained on disk cache when the file is
released. The user can override the default on a
file-by-file basis by specifying a size when
marking a file for partial release. For more
information, see the release(1) man page.
For n, specify an integer from 8 to whatever has
been set for the maxpartial option. For more
information on maxpartial, see the maxpartial
option in this list. The default is 16.
maxpartial=n
Sets the maximum partial release size for the file
system to n kilobytes. The partial release size
cannot be set larger than this maxpartial setting.
For n, specify an integer such that 0 < n <
2097152. The default is 16.
partial_stage=n
Sets the partial stage size for the file system to
n kilobytes. For a partial release file, this
value specifies the offset in the file past which
access results in the entire file being staged to
disk. For n, specify a integer from 0 to whatever
has been set for the maxpartial option. The
default is equal to whatever has been set for the
partial option.
stage_n_window=n
Sets the stage -n buffer size for the file system
to n kilobytes. This option applies to files that
are read directly from the archive media. This
attribute is set by using the stage(1) command's
-n option. For a file with this attribute, this
is the size that is staged in to the application's
buffer at any one time. For n, specify an integer
such that 64 < n < 2097152. The default is 8192.
If the total number of outstanding stage_n buffers
is less than physical memory, the access is not
NFS, and the stage_n_window is less than 1%
physical memory, then the buffer is allocated in
pageable memory. Otherwise, blocks are allocated
for the buffer from the file system. Note, the
SAM-QFS shared file system does not support stage
-n from a client.
stage_flush_behind=n
Sets the maximum stage flush behind value to n
kilobytes. Stage pages that are being staged are
written to disk asynchronously to help the Solaris
VM layer keep pages clean. For n, specify an
integer such that 0 < n < 8192. The default is 0,
which means that stage flush behind is disabled.
hwm_archive
Invokes the archiver when the amount of data in
the file system increases above the high-water
mark.
SHARED FILE SYSTEM OPTIONS
The following options are supported for Sun QFS and SAM-QFS
shared file systems.
Both file system equipment types ms and ma are supported.
For a description of the ma and ms file systems, see the
mcf(4) man page. For a description of the Sun QFS shared
file system, see the Sun QFS Configuration and
Administration Guide.
The stripe width is set by default to round robin (using the
stripe=0 mount option).
shared Specifies that the file system being mounted is a
Sun QFS shared file system. The shared option
must be specified in the /etc/vfstab file because
it is used in the boot initialization sequence.
bg Specifies that if the first mount attempt fails,
the system should retry the mount in the
background. If bg is not specified, the mount
continues in the foreground.
retry=n Specifies the number of times to retry the mount
operation. For n, specify an integer such that 0
< n < 20000. By default, n=10000.
minallocsz=n
Sets the minimum block allocation value for the
Sun QFS shared file system to n. Specify n in
units of kilobytes and as a multiple of 8
kilobytes. The minallocsz option specifies the
minimum number of bytes that are allocated ahead
of a write for a Sun QFS shared file system. For
n, specify an integer such that 16 < n < 2097152.
By default, n=8 * allocation_unit (DAU). See
sammkfs(1M) command's -a option.
maxallocsz=n
Sets the maximum block allocation value for the
Sun QFS shared file system to n. Specify n in
units of kilobytes and as a multiple of 8
kilobytes. The maxallocsz option specifies the
maximum number of bytes that are allocated ahead
of a write for a Sun QFS shared file system. For
n, specify an integer such that 16 < n < 4194304.
By default, n=128 * allocation_unit (DAU). See
sammkfs(1M) command's -a option.
rdlease=n Sets the read lease time for the Sun QFS shared
file system to n seconds. The rdlease option
specifies the maximum number of seconds that a
file can be read before reacquiring the read
lease. For n, specify an integer such that 15 < n
< 600. By default, n=30.
wrlease=n Sets the write lease time for the Sun QFS shared
file system to n seconds. Only one host can write
to a file at any one time unless the mh_write
option is set on the metadata server. If the
mh_write option is set on the metadata server,
multiple hosts can write to and read from the same
file at the same time. If multiple hosts are
writing, the last write is the one that is
effective. The wrlease option specifies the
maximum number of seconds that a file can be
written before reacquiring the write lease. For
n, specify an integer such that 15 < n < 600. By
default, n=30.
aplease=n Sets the append lease time for the Sun QFS shared
file system to n seconds. Only one host can
append to a file at any one time. The aplease
option specifies the maximum number of seconds
that one host can append to a file before
reacquiring the append lease. For n, specify an
integer such that 15 < n < 600. By default, n=30.
mh_write Enables simultaneous reads and writes to the same
file from multiple hosts. If mh_write is used,
the Sun QFS shared file system switches all hosts
into directio. The application must use page
aligned memory buffers and well formed sector I/O
(512 bytes). Caution, if the application does not
adhere to these alignment rules, data correctness
is not guaranteed.
This option is effective only on the metadata
server host. If this option is specified when
mounting the file system on a client host, it is
ignored. If the client host becomes the metadata
server in the future, however, this option becomes
effective. For this reason, it is recommended to
use this mount option on the metadata host and all
potential metadata server hosts. If the mh_write
option is not specified on the metadata server,
only one host can write at any one time to a
single file.
min_pool=n
Sets the minimum number of shared file system
threads to keep around. The number of threads
grows and shrinks dynamically based on load. This
parameter tells the system to keep at least that
many threads in the active pool. For n, specify
an integer such that 8 < n < 2048. The default
n=64. For Linux the default n=8. NOTE: The
min_pool parameter must be set in samfs.cmd file.
It is ignored if set in the /etc/vfstab file or on
the mount(1M) command.
nstreams=n
* No longer used. *
meta_timeo=n
Allow attributes and directory data to be cached
by a host system for up to n seconds before
checking for consistency with the metadata server.
The default n=3.
Example 1. With the default setting of
meta_timeo=3, the file system verifies attribute
and directory consistency with the metadata server
at least every 3 seconds. For instance, a new
file created on one host may not be seen by an
ls(1) command on another host for up to 3 seconds.
Example 2. If meta_timeo=0, the file system
verifies attribute and directory consistency with
the metadata server before each use. The cattr
mount option can be used with meta_timeo=0 to
ensure that changes made by other hosts currently
modifying a file are also immediately visible.
Example 3. If meta_timeo=3, with the nocattr
mount option (default), the file system verifies
attribute consistency if it has not been checked
in the past 3 seconds; however, attribute changes
made by a client host which is currently modifying
a file may not be detected until the client lease
time has expired.
Example 4. If meta_timeo=3, with the cattr mount
option, the file system verifies attribute
consistency if it has not been checked in the past
3 seconds, and also ensures that attribute changes
made by other hosts are detected within that time
interval.
cattr | nocattr
Enable (disable) attribute consistency checking.
If cattr is set, the file system ensures that
attribute changes made by a host which is
modifying a file are visible to other hosts within
the meta_timeo interval. (Directories are not
affected by cattr; directory modifications are
always visible within the time interval set by
meta_timeo.)
With the default setting of nocattr, attribute
changes made by a host (in particular, file size
and modification time) may not be visible to other
hosts until the write or append lease time has
expired.
Note that enabling cattr may adversely affect
performance, as additional network traffic is
required.
lease_timeo=n
The read, write, and/or append lease for a single
file is relinquished if it is not being used after
n seconds. lease_timeo varies from -1 to 15
seconds. If lease_timeo is >=0, the lease is
relinquished if it is not being used after n
seconds. If lease_timeo is set to -1, the lease
is not relinquished and the lease expires based on
the lease time. Note, the read and write lease is
not relinquished if mh_write is set because
multiple reader/writer hosts are enabled. The
default n is 0.
MULTIREADER FILE SYSTEM OPTIONS
The following options support the single-writer, multireader
file system. This file system is mounted on one host system
as a single-writer file system that updates the file system.
In addition, this file system can be mounted on one or more
host systems as a multireader file system.
These options can be specified only on Sun QFS file systems.
The writer option cannot be used if you are mounting the
file system as a Sun QFS shared file system, however, the
reader option is supported. Note, sync_meta should be set to
1 if the reader option is used in a Sun QFS shared file
system.
A major difference between the multireader file system and
Sun QFS shared file system is that the multireader host
reads metadata from the disk, and the client hosts of a Sun
QFS shared file system read metadata over the network.
The system administrator must ensure that only one host in a
multireader file system has the file system mounted with the
writer mount option enabled.
writer Sets the file system to type writer. There can be
only one host system that has the file system
mounted with the writer option at any one time.
If writer is specified, files are flushed to disk
at close and directories are always written
through to disk. The option atime = 1 is set for
writer.
Prior to the 4.0 release, the writer option was
specified as the shared_writer option. The older
syntax is supported for backward compatibility.
reader Sets the file system to type reader. This mounts
the file system as read only. There is no limit
to the number of host systems that can have the
same file system mounted with the reader option.
By default, each lookup checks the inode and
refreshes the inode pages if the inode has been
modified by the writer host. If the invalid
option is set to a value greater than 0, the inode
is checked for modification only after it has aged
invalid seconds after the last check; for more
information, see the invalid option.
Prior to the 4.0 release, the reader option was
specified as the shared_reader option. The older
syntax is supported for backward compatibility.
invalid=n When specified in conjunction with the reader
option, holds cached attributes for the
multireader file system at least n seconds after
file modification. Caution, it is possible to
read stale data if invalid is set to a nonzero
value. For n, specify an integer such that
0 < n < 60. By default, n=0.
Example 1. If invalid=0, which is the default,
the file system always checks to see if the inode
is stale. That is, it checks to see if the inode
has been changed by the writer host.
Example 2. If invalid=30, the file system checks
the inode 30 seconds after the last check. This
means that if you issue an ls(1) command, you
might not see a new file for 30 seconds after it
has been created on the writer host. This also
means that if you open an existing file, for
example with the cat(1) command, you might not see
any changes made to the file on the writer host in
the past 30 seconds.
refresh_at_eof
When specified in conjunction with the reader
option, the current file size is refreshed when
the read buffer exceeds the end of file.
SUN QFS OPTIONS
The following options are supported only for Sun QFS and
SAM-QFS file systems on ma Equipment Type file systems. For
more information on the ma file system Equipment Type, see
the mcf(4) man page.
mm_stripe=n
Sets the metadata stripe width for the file system
to n 16-kilobyte disk allocation units (DAUs). By
default, mm_stripe=1, which writes one DAU of
metadata to one LUN before switching to another
LUN. If mm_stripe=0, the metadata is round
robined across all available metadata LUNs.
FILES
/etc/mnttab Table of mounted file systems.
/etc/vfstab List of default parameters for each file
system.
/etc/opt/SUNWsamfs/samfs.cmd
List of default and global parameters
for SAM-QFS file systems. For more
information, see the samfs.cmd(4) man
page.
SEE ALSO
release(1), setfa(1), ssum(1).
mount(1M), mountall(1M), sam-fsalogd(1M), sam-releaser(1M),
sammkfs(1M), umount_samfs(1M).
mount(2).
sam_setfa(3), sam_advise(3), directio(3C).
mcf(4), mnttab(4), samfs.cmd(4), vfstab(4).
NOTES
If the directory upon which a file system is to be mounted
is a symbolic link, the file system is mounted on the
directory to which the symbolic link refers, rather than on
top of the symbolic link itself.
The mount parameters can be provided in the samfs.cmd file,
in the /etc/vfstab file, and on the mount(1M) command.
Specifications in the /etc/vfstab file override the
directives in the samfs.cmd file, and options to the
mount(1M) command override specifications in the /etc/vfstab
file.
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