Windows PowerShell command on Get-command fssnap

Manual Pages for UNIX Operating System command usage for man fssnap_ufs

System Administration Commands fssnap_ufs(1M)

NAME

fssnap_ufs - create a temporary snapshot of a UFS file sys-

tem

SYNOPSIS

fssnap [-F ufs] [-V] -o backing-store=path,

[specific-options] /mount/point

fssnap -d [-F ufs] [-V] /mount/point | dev

fssnap -i [-F ufs] [-V] [-o specific-options] /mount/point | dev

DESCRIPTION

The fssnap command queries, creates, or deletes a temporary

snapshot of a UFS file system. A snapshot is a point-in-time

image of a file system that provides a stable and unchanging device interface for backups. When creating a file system snapshot, you must specify the

file system to be captured and the backing-store file. The

backing-store file(s) are where the snapshot subsystem saves

old file system data before it is overwritten. Beyond the

first backing-store file, fssnap automatically creates addi-

tional backing-store files on an as-needed basis.

The number and size of the backing store files varies with the amount of activity in the file system. The destination

path must have enough free space to hold the backing-store

file(s). This location must be different from the file sys-

tem that is being captured in a snapshot. The backing-store

file(s) can reside on any type of file system, including

another UFS file system or an NFS-mounted file system.

OPTIONS The following options are supported:

-d

Deletes the snapshot associated with the given file sys-

tem.

-i

Displays the state of one or all UFS snapshots. If a

mount-point or device is not specified, a list of all

snapshots on the system is displayed. When a mount-point

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System Administration Commands fssnap_ufs(1M)

or device is specified, detailed information is provided for the specified file system snapshot by default.

Use the -o options with the -i option to specify what

snapshot information is displayed. Since this feature is provided primarily for use in scripts and on the command line, no labels are displayed for the data. Sizes are all in bytes, and the output is not internationalized or localized. The information is displayed on one line per option. Unrecognized options display a single ? on the line. One line per option guarantees that there are the same number of lines as options specified and there is a

one-to-one correspondence between an output line and an

option.

The following -o options display specific information

for a given snapshot. See the EXAMPLES section for exam-

ples of how to use these options. snapnumber Display the snapshot number. blockdevname Display the block device path. rawdevname Display the raw device path. mountpoint Display the mount point of the master file system. state Display the state of the snapshot device.

backing-store

Display the location of the first backing-store file

for this snapshot. If there are multiple backing-

store files, subsequent files have the same name as the first file, with the suffixes .2, .3, and so forth.

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System Administration Commands fssnap_ufs(1M)

backing-store-len

Display the sum of the sizes of the backing-store

files. maxsize Display the maxsize value specified for the

backing-store file(s).

createtime Display the time that the snapshot was created. chunksize

Display the copy-on-write granularity.

-o specific-options

Without -d or -i, the default action is to create a

snapshot. Specify the following options when creating a snapshot. All of these options are discretionary, except

for the backing-store file, which is required.

backing-store=path

Uses path in the creation of the backing-store

file(s). path must not reside on the file system that is being captured in a snapshot and must not be

the name of an existing file. If path is a direc-

tory, then a backing-store file is created within it

using a name that is generated automatically. If path is not a directory and does not already exist,

then a backing-store file with that name is created.

If more than one backing-store file is required,

fssnap creates subsequent files automatically. The second and subsequent files have the same name as the first file, with suffixes of .2, .3, and so forth. This option can be abbreviated as bf=path or bs=path. unlink

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Unlinks the backing-store file after the snapshot is

created. This option specifies that the backing-

store file does not need to be removed manually when

the snapshot is deleted. This might make administra-

tion more difficult since the file is not visible in the file system. If this option is not specified,

the backing-store files should be removed manually

after the snapshot is deleted. chunksize=n [k,m,g]

Uses n for the chunk size. Chunk size is the granu-

larity of the data that is sent to the backing store. Specify chunksize in the following units: k for kilobytes, m for megabytes, or g for gigabytes. By default, chunk size is four times the block size of the file system (typically 32k). maxsize=n[k,m,g]

Does not allow the sum of the sizes of the backing-

store file(s) to exceed n, where n is the unit specified. The snapshot is deleted automatically

when the sum of the sizes of the backing-store

file(s) exceeds maxsize.

Specify maxsize in the following units: k for kilo-

bytes, m for megabytes, or g for gigabytes. raw

Displays to standard output the name of the raw dev-

ice instead of the block device when a snapshot is created. The block device is printed by default (when raw is not specified). This option makes it easier to embed fssnap commands in the command line for commands that require the raw device instead. Both devices are always created. This option affects only the output. OPERANDS The following operands are supported:

mount-point

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The directory where the file system resides. special The physical device for the file system, such as /dev/dsk/c0t0d0s7.

EXAMPLES

Example 1 Creating a Snapshot of a File System The following example creates a snapshot of a file system. The block special device created for the snapshot is /dev/fssnap/0.

# fssnap -F ufs -o backing-store=/var/tmp /export/home

/dev/fssnap/0 Example 2 Backing Up a File System Snapshot Without Having To Unmount the File System The following example backs up a file system snapshot without having to unmount the file system. Since ufsdump requires the path to a raw device, the raw option is used. The /export/home file system snapshot is removed in the second command.

# ufsdump 0uf /dev/rmt/0 `fssnap -F ufs

-o raw,bs=/export/snap /export/home`

# fssnap -F ufs -d /export/home

Example 3 Backing Up a File System

When backing up a file system, do not let the backing-store

file(s) exceed 400 Mbytes. The second command removes the /export/home file system snapshot.

# ufsdump 0uf /dev/rmt/0 `fssnap -F ufs

-o maxsize=400m,backing-store=/export/snap,raw

/export/home`

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# fssnap -F ufs -d /export/home

Example 4 Performing an Incremental Dump of a Snapshot The following example uses ufsdump to back up a snapshot of /var. Note the use of the N option to ufsdump, which writes the name of the device being dumped, rather than the name of the snapshot device, to /etc/dumpdates file. See ufsdump(1M) for details on the N flag.

# ufsdump lfNu /dev/rmt/0 /dev/rdsk/c0t3d0s2 `fssnap -F ufs

-o raw,bs=/export/scratch,unlink /var`

Example 5 Finding Out What Snapshots Currently Exist The following command displays the currently existing snapshots.

# fssnap -i

0 /src 1 /export/home Example 6 Mounting a File System Snapshot The following example creates a file system snapshot. After you create a file system snapshot, mount it on /tmp/mount

for temporary read-only access.

# fssnap -F ufs -o backing-store=/nfs/server/scratch /export/home

/dev/fssnap/1

# mkdir /tmp/mount

# mount -F ufs -o ro /dev/fssnap/1 /tmp/mount

Example 7 Creating a File System Snapshot and Unlinking the

Backing-store File

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The following example creates a file system snapshot and

unlinks the backing-store file. After creating a file system

snapshot and unlinking the backing-store file, check the

state of the snapshot.

# fssnap -o bs=/scratch,unlink /src

/dev/fssnap/0

# fssnap -i /src

Snapshot number : 0 Block Device : /dev/fssnap/0 Raw Device : /dev/rfssnap/0 Mount point : /src Device state : active Backing store path : /scratch/snapshot2 Backing store size : 192 KB Maximum backing store size : Unlimited Snapshot create time : Sat May 06 10:55:11 2000

Copy-on-write granularity : 32 KB

Example 8 Displaying the Size and Location of the Backing-

store File(s) and the Creation Time for the Snapshot

The following example displays the size of the backing-store

file(s) in bytes, the location of the backing store, and the creation time for the snapshot of the /test file system.

# fssnap -i -o backing-store-len,backing-store,createtime /test

196608 /snapshot2 Sat May 6 10:55:11 2000

Note that if there are multiple backing-store files stored

in /snapshot2, they will have names of the form file (for the first file), file.1, file.2, and so forth. EXIT STATUS The following exit values are returned: 0 Successful completion.

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>0 An error occurred.

ATTRIBUTES

See attributes(5) for descriptions of the following attri-

butes:

____________________________________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

|_____________________________|_____________________________|

| Availability | SUNWcs |

|_____________________________|_____________________________|

The script-readable output mode is a stable interface that

can be added to, but will not change. All other interfaces are subject to change.

System Administration Commands fssnap_ufs(1M)

o The file system is used as backing store by an application that uses mlock(3C) to lock its pages. Typically, these are real time applications, such as ntpd (delivered in the SUNWntpu package). These conditions result in fssnap being unable to write lock the file system prior to performing the snapshot.

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Manual Pages for UNIX Operating System command usage for man fssnap_ufs

System Administration Commands fssnap_ufs(1M)

NAME

fssnap_ufs - create a temporary snapshot of a UFS file sys-

SYNOPSIS

DESCRIPTION

System Administration Commands fssnap_ufs(1M)

for a given snapshot. See the EXAMPLES section for exam-

System Administration Commands fssnap_ufs(1M)

System Administration Commands fssnap_ufs(1M)

System Administration Commands fssnap_ufs(1M)

EXAMPLES

System Administration Commands fssnap_ufs(1M)

System Administration Commands fssnap_ufs(1M)

System Administration Commands fssnap_ufs(1M)

ATTRIBUTES

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

SEE ALSO

System Administration Commands fssnap_ufs(1M)