This chapter describes procedures that you can use to perform system administration. After installation, Sun Prestoserve requires attention only when you need to change the system configuration.
To run Sun Prestoserve, use the presto command. There are several options available with this command.
Invoked with no options, the state of the Sun Prestoserve device is printed out.
Many of the functions that presto supports can be executed remotely by specifying the name of the remote host using the -h option with the presto command.
Activates the Sun Prestoserve driver. When Sun Prestoserve is installed, the shell script /etc/rc.local is modified to include a presto -u command. This causes Sun Prestoserve to be brought into the UP state. /etc/rc.local is executed automatically when the system is brought up in the multi-user mode. The presto -u command actually performs two functions. First, it performs an ioctl on the /dev/pr0 device to bring Sun Prestoserve to the UP state. Second, it scans the /etc/fstab and /etc/mtab files and enables Sun Prestoserve caching on each local device which is writable ("rw" mode) and not of type "swap".
Prints a list (in a mount-like format) of all the filesystems which are being accelerated by Sun Prestoserve.
Sets the state of the Sun Prestoserve device to DOWN after flushing any dirty buffers.
Similar to presto -d, but in the event that dirty data could not be flushed due to an error condition, it is discarded. This command can cause data to be lost, so it should only be used in unusual error situations (see "Serious Disk Failures" on page 5-5).
Prints information about the state of the Sun Prestoserve hardware and accumulated statistics on read and write operations passing through Sun Prestoserve.
Note - The hit rate for writes gives an indication of how effective the Sun Prestoserve cache is, since each dirty hit represents a physical disk write that was avoided entirely. If you discover that the number of read operations is very high in proportion to the total count of read and write operations (say, 75% or more), you may find that increasing the amount of main memory on the server will help system performance.
Use the information provided in this section to remove, transfer to a new system, or store the Sun Prestoserve card.
The Sun Prestoserve card should be thought of as a piece of your disks. If you experience a power outage, a system panic, or abort the machine the Sun Prestoserve driver cannot flush cached data to the disk. In this state, removing the card is like removing a piece of the disk. Shutdowns that leave valid data on the Sun Prestoserve card are termed unclean shutdowns.
Caution -
Follow these steps to remove the SBus Prestoserve card:
To ensure that no valid data is contained on the Sun Prestoserve card, make sure that Sun Prestoserve is in the PRDOWN state by using the presto -d command, or halt the operating system as usual. Halting the operating system works because the Sun Prestoserve driver ensures that dirty data is flushed from the cache when the system is shut down.
The CHECK DATA button is located on the Sun Prestoserve SBus faceplate, which appears in a cutout slot on the back of the CPU board. The DATA OK LED which is next to the button does not light if all dirty data has been written. If the LED does light, either there was a disk error which prevented writing of all the cached data, or the system was not shutdown properly. If this is the case, reboot the system and correct any disk errors (see Chapter 5, "Abnormal Operations"). Then halt the system gracefully.
This should unplug the board from the backplane connectors and back it out of the cardcage about 1/4".
Caution -
Bring the system back up by turning on the power and rebooting.
The Sun SBusPrestoserve card has two permanently-mounted lithium batteries that maintain the non-volatile memory cache in case of power loss. These batteries last at least eight years in a running system, or in storage with the batteries disabled. The batteries last approximately two years in a powered down system or in storage with the batteries enabled.
Note - Lighting the LED when running strictly on battery power can significantly reduce battery lifetime.
The Sun Prestoserve driver monitors the state of the batteries, and a console message is displayed when the battery state changes. When both batteries fall below their nominal voltage levels, Sun Prestoserve disables its functions, and all subsequent disk requests are passed directly to the drivers.
If a battery fails, call your authorized Sun service provider.
Caution -
In some situations you may want to disable the batteries on the Sun Prestoserve card. If you disable the batteries for five minutes or longer, the memory is lost and its contents are cleared.
Follow these steps to disable the batteries:
If you need to store the Sun Prestoserve card for a long period follow these steps to avoid draining the batteries:
After you have removed Sun Prestoserve, you can safely move the card to a different system. If you must move a card containing valid data, consult Chapter 5, "Abnormal Operations."
If you need to remove a Sun Prestoserve card containing live data and it is essential that no one have access to this data, the memory on the card can be cleared by disabling the batteries as described above.
This section identifies what actions need to be taken when the configuration of the server changes. Such changes include adding or deleting accelerated filesystems, changing the hardware configuration (new disk, new CPU, removable disk packs), and new releases of operating system software.
When you are selecting filesystems to be accelerated with Sun Prestoserve, choose filesystems that receive synchronous write requests.
Note - Accelerating other file systems provides no significant benefit and may result in a minor overall performance degradation by burdening the Sun Prestoserve driver with additional data structures to maintain.
Local swap partitions and read-only filesystems do not generate synchronous writes and are not normally Presto-ized. Filesystems accessed via NFS receive the most significant benefit from Sun Prestoserve, since many requests for such files are synchronous. Similar performance gains can be realized on filesystems that are used heavily by applications that do synchronous I/O. Local filesystems can also benefit from Sun Prestoserve because operations such as creating or removing a file generate synchronous writes. Remote swapping done to NFS files benefits from Sun Prestoserve. In most cases, it should not be necessary to alter the default selection of accelerated filesystems.
To unaccelerate or reaccelerate a specific filesystem, the presto -d and presto -u commands may be issued with an argument that identifies the filesystem by naming its mount point or the block-special-file to be affected:
# presto -u filesystem
If you mount a local filesystem using the mount command after the system is running multi-user, it is necessary to run the presto -u command again to cause that filesystem to be accelerated by Sun Prestoserve.
If you add or remove disks and controllers, or change CPU boards or ID PROMS, no special administration is needed as long as you ensure that Sun Prestoserve is in the DOWN state prior to reconfiguring your machine. This can be achieved by using the presto -d command, or by cleanly shutting down the operating system according the instructions provided with the software.
If you have removable disk packs, you must invoke the presto -d filesystem command before you run umount. Once this is complete, you can physically remove the disk pack. (Sun Prestoserve does not need to be in the DOWN state).
If you upgrade from one version of SunOS 4.x to another version of SunOS 4.x, Sun Prestoserve should continue to work. However, if you upgrade from Solaris 2.0 to Solaris 2.1 or from SunOS 4.x to Solaris 2.1 a Prestoserve upgrade is required. Check with your Sun sales representative to confirm that a Sun Prestoserve upgrade is required.
Before installing the new release, remove Sun Prestoserve using the
presto_chango -r command. After installing the new operating system
software follow the installation instructions that come with your Prestoserve
kit. The Sun Prestoserve card can be left in place. If any non-Sun-standard disk
controllers have been configured for use with Sun Prestoserve, you need to re-
enable those controllers. Consult the documentation that comes with the
Prestoserve option for the specific commands.
