This chapter provides information about maintaining ONC3/NFS. It explains how to change the default number of NFS daemons and modify automatic mounter maps. It also gives suggestions for using alternative mounting techniques and avoiding mount point conflicts. It also describes how to modify and delete CacheFS file systems.
This chapter contains these sections:
Systems set up for NFS normally run four nfsd daemons. nfsd daemons, called NFS server daemons, accept RPC calls from clients. Four NFS server daemons might be inadequate for the amount of NFS traffic on your server. Degraded NFS performance on clients is usually an indication that their server is overloaded.
To change the number of NFS server daemons, create the file /etc/config/nfsd.options on the server if it doesn't already exist and specify the number of daemons to start at system startup. For example, to have the /etc/init.d/network script start eight nfsd daemons, the /etc/config/nfsd.options file needs to look like this:
cat /etc/config/nfsd.options 8 |
Modify this number only if a server is overloaded with NFS traffic. In addition to increasing NFS daemons, consider adding another server to your NFS setup. The maximum recommended number of NFS daemons is 24 on a large server. If you increase the number of NFS server daemons, confirm your choice by giving this command:
/usr/etc/nfsstat -s Server NFS V3: calls badcalls 2284031 0 null getattr setattr lookup access readlink 0 0% 550622 24% 8701 0% 625503 27% 512426 22% 68368 2% read write create mkdir symlink mknod 385682 16% 2965 0% 126 0% 3 0% 138 0% 0 0% remove rmdir rename link readdir readdir+ 327 0% 40 0% 55 0% 1 0% 76 0% 21574 0% fsstat fsinfo pathconf commit 83056 3% 24033 1% 16 0% 319 0% |
If the output shows many null receives, you should consider lowering the number of NFS server daemons. There is no exact formula for choosing the number of NFS daemons, but here are several rules of thumb you can consider:
One nfsd for each CPU plus one to three nfsds as a general resource
One nfsd for each disk controller plus one to three nfsds as a general resource (a logical volume counts as one controller, no matter how many real controllers it is spread over)
One nfsd for each CPU, one nfsd for each controller, and one to three nfsds as a general resource
In cases where an NFS client requires directories not listed in its /etc/fstab file, you can use manual mounting to temporarily make the NFS resource available. With temporary mounting, you need to supply all the necessary information to the mount program through the command line. As with any mount, a temporarily mounted directory requires that a mount point be created before mounting can occur.
For example, to mount /usr/demos from the server redwood to a local mount point /n/demos with read-only, hard, interrupt, and background options, as superuser, give these commands:
mkdir -p /n/demos mount –o ro,bg redwood:/usr/demos /n/demos |
A temporarily mounted directory remains in effect until the system is rebooted or until the superuser manually unmounts it. Use this method for one-time mounts.
You can modify the automatic mounter maps at any time. AutoFS accepts map modifications at any time, without having to restart the daemon. Simply make the change and run the command /usr/etc/autofs -v. This command reconciles any differences between /etc/mtab and the current map information.
With automount, some of your modifications take effect the next time the automatic mounter accesses the map, and others take effect when the system is rebooted. Whether or not booting is required depends on the type of map you modify and the kind of modification you introduce.
Rebooting is generally the most effective way to restart automount. You can also kill and restart the automatic mounter using automount at the command line. Use this method sparingly, however. (See the automount(1M).)
automount consults the master map only at startup time. A modification to the master map (/etc/auto.master) takes effect only after the system has been rebooted or automount is restarted (see “Modifying Direct Maps”). With AutofS, the change takes effect after the autofs command is run.
You can modify, delete, or add to indirect maps (the files listed in /etc/auto.master or /etc/auto_master) at any time. Any change takes effect the next time the map is used, which is the next time a mount is requested.
Each entry in a direct map is an automount or autofs mount point, and the daemon mounts itself at these mount points at startup, and with AutoFS, when autofs is run. With autofs, the changes are noted immediately, since it stays in sync with /etc/mtab.
With automount, adding or deleting an entry in a direct map takes effect only after you have gracefully killed and restarted the automountd daemon or rebooted. However, except for the name of the mount point, you can modify direct map entries while automount is running. The modifications take effect when the entry is next mounted, because automount consults the direct maps whenever a mount must be done.
For instance, with automount, suppose you modify the file /etc/auto.indirect so that the directory /usr/src is mounted from a different server. The new entry takes effect immediately (if /usr/src is not mounted at this time) when you try to access it. If it is mounted now, you can wait until automatic unmounting takes place to access it. If this is not satisfactory, unmount the directory with the umount command, notify automount with the command /etc/killall -HUP automount that the mount table has changed, and then access the directory. The mounting should be done from the new server. However, if you want to delete the entry, you must gracefully kill and restart the automount daemon. The automount process must be killed with the SIGTERM signal:
/etc/killall -TERM automount |
You can then manually restart automount or reboot the system.
 | Note: If gracefully killing and manually restarting automount does not work, rebooting the system should always work. |
You can cause a mount conflict by mounting one directory on top of another. For example, say you have a local partition mounted on /home, and you want automount to mount other home directories. If the automount maps specify /home as a mount point, automount hides the local home partition whenever it mounts.
The solution is to mount the server's /home partition somewhere else, such as /export/home, for example. You need an entry in /etc/fstab like this:
/net/home /export/home xfs rw,raw=/dev/rhome 0 0 |
This example assumes that the master file contains a line similar to this:
/home /etc/auto.home |
It also assumes an entry in /etc/auto.home like this:
terra terra:/export/home |
where terra is the name of the system.
| Note: Before changing parameters for a cache, you must unmount all file systems in the cache directory with the umount command. |
The following command changes the value of one or more parameters:
cfsadmin -u –o parameter_list cache_directory |
| Note: You can only increase the size of a cache, either by number of blocks or number of inodes. If you want to make a cache smaller, you must remove it and re-create it with new values. |
The following commands unmount /local/cache3 and change the threshfiles parameter to 65%:
# umount /local/cache3 # cfsadmin -u -o threshfiles=65 /local/cache3 |
The following command returns information about all file systems cached under the specified cache directory.
cfsadmin -l cache_directory |
| Note: The block size reported by cfsadmin is in 8 Kbyte blocks. |
The following command shows information about the cache directory named /usr/cache/nabokov:
# cfsadmin -l /usr/cache/nabokov |
cfsadmin: list cache FS information
Version 2 4 50
maxblocks 90% (1745743 blocks)
hiblocks 85% (1648757 blocks)
lowblocks 75% (1454786 blocks)
maxfiles 90% (188570 files)
hifiles 85% (178094 files)
lowfiles 75% (157142 files)
neteng:_old-root-6.2_usr_local_lib:_usr_local_lib
neteng:_usr_annex:_usr_annex
bitbucket:_b_jmy:_usr_people_jmy_work
neteng:_old-root-6.2_usr_local_bin:_usr_local_bin
|
This example shows multiple mount points for a single cache: neteng and bitbucket.
The following command deletes a file system in a cache:
cfsadmin –d cache_id cache_directory |
| Note: Before deleting a cached file system, you must unmount all the cached files systems for that cache directory. |
The cache ID is part of the information returned by cfsadmin –l.
The following commands unmount a cached file system and delete it from the cache:
# umount /usr/work # cfsadmin -d _dev_dsk_c0t1d0s7 /local/cache1 |
You can delete all file systems in a particular cache by using all as an argument to the –d option. The following command deletes all file systems cached under /local/cache1:
# cfsadmin -d all /local/cache1 |
The all argument to –d also deletes the specified cache directory.