presto man page on Ultrix

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presto(8)							     presto(8)

Name
       presto - control and monitor the Prestoserve file system accelerator

Syntax
       /usr/etc/presto [ options ]

Description
       The command allows you to get Prestoserve information and to administer
       Prestoserve from a local machine that is running the Prestoserve	 soft‐
       ware or from a remote machine that is running the Prestoserve software.

       If  invoked with no options, displays the Prestoserve state (either UP,
       DOWN, or	 ERROR),  the  number  of  bytes  of  nonvolatile  memory  the
       Prestoserve  cache  is  using, how long the cache has been enabled, the
       write cache efficiency, and the state of the backup battery or  batter‐
       ies.

       When  the Prestoserve state is UP, Prestoserve improves I/O performance
       to accelerated file systems by caching synchronous  disk	 write	opera‐
       tions to nonvolatile memory.

       When  the  Prestoserve  state  is  DOWN, all I/O requests are passed to
       their intended devices.	Because the Prestoserve state is DOWN after  a
       reboot,	the command should be added to your file to enable file system
       acceleration when the machine reboots.

       If it detects a disk error during a write back, Prestoserve enters  the
       ERROR  state  and  disables  itself.  However, Prestoserve continues to
       maintain the integrity of cached data.  Some possible disk error condi‐
       tions  are:   the  disk	drive  is write protected or off line, a cable
       problem exists, or a bad disk block exists.

       Also, if there is insufficient backup battery power,  Prestoserve  will
       enter the ERROR state.

       By default, all local writable file systems that are mounted are accel‐
       erated when Prestoserve is brought up.

Options
       -d [filesystem...] [blkdev...]
	      Disables Prestoserve and writes the Prestoserve  cache  data  to
	      the  intended  disks.   Only  those  file	 systems  specified by
	      filesystem are  disabled.	  You  can  specify  filesystem	 as  a
	      mounted block device (for example, or as a directory mount point
	      (for example, You can specify  blkdev  for  an  unmounted	 block
	      device  (for  example,  If  no file systems or block devices are
	      specified, all accelerated  file	systems	 and  unmounted	 block
	      devices are disabled, and the Prestoserve state is set to DOWN.

	      This option does not reset Prestoserve statistics.

	      The -d option takes effect before the -u or -R options.

       -F     Writes  the  Prestoserve	cache  data to the intended disks, but
	      leaves the cache data intact.

	      If the option is used and the Prestoserve state is UP, then  the
	      cache  data  is  written	to  the	 intended disks, and the state
	      remains UP.  If the Prestoserve state is DOWN, then there is  no
	      data  to write to the disks, and the state remains DOWN.	If the
	      state is ERROR, then the cache data is written to	 the  intended
	      disks if possible.

	      Note  that  unlike  the  -R  option, the data in the Prestoserve
	      cache remains after it is written to the intended disks.

       -h hostname
	      Invokes the specified operations on the remote machine  hostname
	      by  using an RPC protocol.  You can use the -h option with other
	      command options, but the protocol does not support the -R or  -L
	      options.	The remote machine must be running the daemon to allow
	      the use of the -h option.	 However, the remote machine  must  be
	      running option to allow the use of the -h option and the -u, -d,
	      and -s administrative options.  See for more details.

       -l     Lists the accelerated file systems and their mount points	 in  a
	      format  similar  to  the	command.  This option can be used with
	      either NFS client or server machines.

       -L     Lists all local and remote mounted file systems and their	 mount
	      points, in addition to any block devices that have been acceler‐
	      ated.  Any unusual Prestoserve state for a file system  is  dis‐
	      played after the mount point.  The unusual states include:

	      bounceio	Instead	 of directly accessing the nonvolatile memory,
			the file system's device receives the Prestoserve data
			only after the data is first copied to main memory.

	      disabled	Prestoserve  acceleration  is  not enabled on the file
			system.

	      error	An error occurred  using  the  file  system,  and  the
			Prestoserve cache data has still not been written suc‐
			cessfully to the intended disks.

       -p     Prints Prestoserve information.  The information is grouped into
	      two  areas: the current Prestoserve state and the statistics for
	      write, read, and total operations.  For example:
	      # /usr/etc/presto -p
	      dirty = 52, clean = 7, inval = 0, active = 2
		     count hit rate clean hits dirty hits allocations passes
	      write:  1516	65%	     0	      989	  511	  15
	       read:	 8	 0%	     0		0	    0	   8
	      total:  1524	65%	     0	      989	  511	  23
	      state = UP, size = 0x7e000 bytes
	      statistics interval: 00:00:13  (13 seconds)
	      write cache efficiency: 66%
	      All batteries are ok

	      The current Prestoserve statistics account for  all  Prestoserve
	      buffers.	 A  dirty  buffer contains a disk block image that has
	      not been written to disk.	 A clean buffer contains a valid  disk
	      block image that has been written to disk.  An inval buffer does
	      not presently contain a disk block image.	 An active  buffer  is
	      currently	 in transition to disk, meaning that a write operation
	      has started but has not completed on that buffer.

	      For each Prestoserve cache read or write operation,  Prestoserve
	      increments a counter:

	      ·	  The  clean  hits  counter  shows  the	 number of hits (block
		  matches) on the clean buffers.

	      ·	  The dirty hits counter shows the number of hits on the dirty
		  buffers.   Each  dirty  hit represents a physical disk write
		  that was avoided entirely.

	      ·	  The allocations counter shows the number of new buffers that
		  had to be allocated for disk block images.

	      ·	  The  passes  counter shows the number of I/O operations that
		  Prestoserve passed directly to the real device driver.

	      In addition, for each Prestoserve cache read or write operation,
	      the  command  displays  the  count, which is the sum of the four
	      counters explained previously; the hit rate percentage, which is
	      the  ratio  of  clean hits and dirty hits to the total count and
	      which indicates the effectiveness of the Prestoserve cache;  and
	      the  write  cache	 efficiency percentage, which is computed from
	      the ratio of write dirty hits to the  number  of	writes	copied
	      into the Prestoserve cache.

       -R     Writes  the  Prestoserve	cache data to the intended disks, sets
	      the Prestoserve state to DOWN, purges all	 Prestoserve  buffers,
	      and resets the Prestoserve write and read statistics.

	      Unlike  the  -d  option,	the -R option discards the Prestoserve
	      cache data that could not be written to the intended disks.  The
	      option is useful when Prestoserve cache data is not needed.  You
	      should note that, because the  -R	 option	 destroys  Prestoserve
	      cache data, it should be used carefully.

	      The -R option takes effect before the -u option.

       -s size
	      Sets  the size of the Prestoserve cache to size bytes.  The size
	      can be specified using the decimal or  hexadecimal  conventions.
	      For example, both 262144 and 0x40000 represent 256 Kbytes.

	      If  the  -s  option is used and the current Prestoserve state is
	      UP, the state is set to DOWN, the Prestoserve cache is  resized,
	      and the state is set to UP.

	      You  may	want to use the -s option to determine how Prestoserve
	      performs with a reduced amount of nonvolatile memory.  Note that
	      the  size	 of  the  Prestoserve  cache cannot be larger than the
	      default maximum size.  If you specify a size that is larger than
	      the  default  maximum  size,  the	 default maximum size is used.
	      Refer to the appropriate appendix	 for  your  processor  in  the
	      %%DRPresto%%  for	 information about the default maximum size of
	      nonvolatile memory.

       -u [filesystem...] [blkdev...]
	      Sets Prestoserve state to UP, and enables acceleration.

	      Only those file systems specified	 by  filesystem	 are  enabled.
	      You  can specify filesystem as a mounted block device (for exam‐
	      ple, or as a directory mount point (for example, You can specify
	      blkdev  for  an  unmounted block device (for example, If no file
	      systems are specified, all local writable file systems that  are
	      mounted  will  have  Prestoserve enabled.	 File systems that are
	      presently accelerated will remain accelerated.

	      If the Prestoserve  state	 was  DOWN,  this  option  resets  the
	      Prestoserve statistics and buffers to their initial values.

	      If  Prestoserve  state  was ERROR, Prestoserve attempts to write
	      any blocks that are in the cache to the intended disks  to  make
	      sure that the previous error condition has been corrected.

       -v     Specifies verbose mode.  This option prints extra information to
	      standard output.	The information can be used for debugging pur‐
	      poses.

Files
       Generic Prestoserve control device.

       File where you add the
			 command to accelerate file systems after a reboot.

See Also
       rc(8), prestoctl_svc(8), dxpresto(8X), presto(4)
       Guide to Prestoserve

								     presto(8)
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