программа отслеживания клиентов NFSv4 (NFSv4 Client Tracking Callout Program)
Имя (Name)
nfsdcltrack - NFSv4 Client Tracking Callout Program
Синопсис (Synopsis)
nfsdcltrack [-d] [-f] [-s stable storage dir] <command> <args...>
Описание (Description)
nfsdcltrack is the NFSv4 client tracking callout program. It is
not necessary to install this program on machines that are not
acting as NFSv4 servers.
When a network partition is combined with a server reboot, there
are edge conditions that can cause the server to grant lock
reclaims when other clients have taken conflicting locks in the
interim. A more detailed explanation of this issue is described
in RFC 3530, section 8.6.3 and in RFC 5661, section 8.4.3.
In order to prevent these problems, the server must track a small
amount of per-client information on stable storage. This program
provides the userspace piece of that functionality. When the
kernel needs to manipulate the database that stores this info, it
will execute this program to handle it.
Параметры (Options)
-d, --debug
Enable debug level logging.
-f, --foreground
Log to stderr instead of syslog.
-s storagedir, --storagedir=storage_dir
Directory where stable storage information should be kept.
The default value is /var/lib/nfs/nfsdcltrack.
Команды (Commands)
nfsdcltrack requires a command for each invocation. Supported
commands are:
init
Initialize the database. This command requires no argument.
create
Create a new client record (or update the timestamp on an
existing one). This command requires a hex-encoded
nfs_client_id4 as an argument.
remove
Remove a client record from the database. This command
requires a hex-encoded nfs_client_id4 as an argument.
check
Check to see if a nfs_client_id4 is allowed to reclaim. This
command requires a hex-encoded nfs_client_id4 as an argument.
gracedone
Remove any unreclaimed client records from the database. This
command requires a epoch boot time as an argument.
EXTERNAL CONFIGURATION
The directory for stable storage information can be set via the
file /etc/nfs.conf by setting the storagedir value in the
nfsdcltrack section. For example:
[nfsdcltrack]
storagedir = /shared/nfs/nfsdcltrack
Debuging to syslog can also be enabled by setting "debug = 1" in
this file.
LEGACY TRANSITION MECHANISM
The Linux kernel NFSv4 server has historically tracked this
information on stable storage by manipulating information on the
filesystem directly, in the directory to which
/proc/fs/nfsd/nfsv4recoverydir points. If the kernel passes the
correct information, then nfsdcltrack can use it to allow a
seamless transition from the old client tracking scheme to the
new one.
On a check operation, if there is no record of the client in the
database, nfsdcltrack will look to see if the
NFSDCLTRACK_LEGACY_RECDIR environment variable is set. If it is,
then it will fetch that value and see if a directory exists by
that name. If it does, then the check operation will succeed and
the directory will be removed.
On a gracedone operation, nfsdcltrack will look to see if the
NFSDCLTRACK_LEGACY_TOPDIR environment variable is set. If it is,
then it will attempt to clean out that directory prior to
exiting.
Note that this transition is one-way. If the machine subsequently
reboots back into an older kernel that does not support the
nfsdcltrack upcall then the clients will not be able to recover
their state.
Примечание (Note)
This program requires a kernel that supports the nfsdcltrack
usermodehelper upcall. This support was first added to mainline
kernels in 3.8.
