advfs − A local file system and utilities The POLYCENTER Advanced File System (AdvFS), a file system option on
the DIGITAL UNIX operating system, features rapid crash recovery, high performance, and a flexible structure that
enables you to manage your file system while it is on line. The AdvFS component is licensed with the DIGITAL
UNIX operating system and is available as file system option during installation. A set of utilities that expands the
capabilities of the AdvFS file system is available: The POLYCENTER Advanced File System Utilities. These utilities include capabilities such as adding volumes without reconfiguring the directory hierarchy of the file system,
cloning filesets to enable online backup, and improving system performance with file defragmentation, domain balancing, and file striping. Additionally, a graphical user interface (GUI) that simplifies file system management is
available with the utilities. The POLYCENTER Advanced File System Utilities component is licensed separately
from the DIGITAL UNIX operating system. Using journaling techniques, AdvFS provides faster crash recovery
than the UNIX file system (UFS), which implements crash recovery using the fsck utility. In addition to fast
restarts, AdvFS ensures that file structures are recovered consistently; extends file and fileset sizes to greater than 2
gigabytes; creates, deletes, and renames files faster than UFS; and provides enhanced backup utilities (vdump and
vrestore). By configuring AdvFS as the root filesystem, the preceding AdvFS features are extended to the root
filesystem. A UFS file system corresponds to a disk partition and is, therefore, limited by the size restrictions of that
disk. In contrast, AdvFS filesets can span all volumes in the file domain. AdvFS introduces file system concepts that
do not exist for UFS. Understanding the following concepts prepares you for planning, creating, and maintaining
the AdvFS file system:
Volumes
A volume is any mechanism that behaves like a UNIX block device, such as a disk, disk partition, or logical volume
that is configured with the Logical Storage Manager (LSM).
File Domain
A file domain is a named set of one or more volumes that provides a shared storage pool for one or more filesets (see
filesets below).
When you create a file domain using the mkfdmn command, you must specify a domain name and one initial volume. The mkfdmn command creates a subdirectory in the /etc/fdmns directory for each new file domain. The filedomain subdirectory contains a symbolic link to the initial volume.
You can add additional volumes to an existing file domain by using the addvol utility. With each added volume, the
addvol utility creates a new symbolic link in the appropriate file-domain subdirectory of the fdmns directory.
Filesets
A fileset is both the logical file structure that the user recognizes and a unit that you can mount. Whereas you typically mount an entire UNIX file system, with the AdvFS you mount the individual filesets of a file domain.
An Advanced File System consists of a file domain with at least one fileset that you create using the mkfset command. For each fileset, the mkfset command creates a .tags directory. The .tags directory is a permanent directory
that is reserved for future use. You cannot delete, rename, or add any files to the .tags directory.
Clone Fileset
A clone fileset is a read-only copy of an existing fileset, which you can mount as you do other filesets. You create a
clone fileset by using the clonefset utility. The reason you create and mount a clone fileset is to perform an online
backup of the existing fileset.
A clone fileset is a snapshot of the original fileset, capturing and fixing the original fileset at a moment in time. Any
changes you make to the original fileset will not appear in its clone. For instance, new files added to the original fileset will not appear in the clone. Changes to data in files in the original fileset will not appear in the clone. Also, files
that you remove from the original fileset will remain accessible in the clone under the names they had when you created the clone fileset. The following list summarizes the AdvFS commands:
Displays file system statistics. See advfsstat(8). Locates AdvFS partitions on disks. See advscan(8). Changes the
attributes of a file. See chfile(8).
Changes the attributes of a fileset. See chfsets(8). Changes the attributes of a volume. See chvol(8). Edits the user
or group quotas. See edquota(8).
Creates a new file domain. See mkfdmn(8). Creates a fileset within an existing file domain. See mkfset(8). Checks
for mounted AdvFS filesets. See mountlist(8).
Creates a list of files on specified filesets, including the path names and i-numbers. See ncheck(8). Summarizes
fileset ownership. See quot(8).
Displays disk usage and limits. See quota(1). Checks file system quota consistency. See quotacheck(8). Turns on
user and group quotas. See quotaon(8).
Turns off user and group quotas. See quotaoff(8). Renames an existing fileset. See renamefset(8). Summarizes
the disk usage and quotas for specified filesets. See repquota(8).
Removes an unused file domain from AdvFS. See rmfdmn(8). Deletes a fileset from a file domain. See rmfset(8).
Displays unformatted disk blocks. See shblk(8).
Displays frag file information. See shfragbf(8). Displays domain attributes. See showfdmn(8). Displays attributes
for files in an Advanced File System. See showfile(8).
Displays information about the filesets in a domain. See showfsets(8). Moves the AdvFS log file to a different volume in a file domain. See switchlog(8).
Prints the path name of a file, given the tag number. See tag2name(8). Displays mcells that describe metadata for a
file. See vbmtchain(8).
Displays a formatted page of the bitfile metadata table (BMT). See vbmtpg(8). Backs up filesets. See vdump(8).
Checks for and repairs file system inconsistencies. See verify(8).
Displays the contents of a file from an unmounted domain. See vfile(8). Prints a single header page of a frag file.
See vfragpg(8).
Displays a formatted page of the log. See vlogpg(8). Displays the logical sequence number (LSN) of a page of the
log. See vlsnpg(8).
Restores files from devices written with the vdump command. See vrestore(8). Displays a formatted page of the
tag directory. See vtagpg(8). Operations supported by the following AdvFS commands will be retired in a future release of the DIGITAL UNIX operating system and are supported only for backward compatibility with operating
system versions earlier than DIGITAL UNIX Version 4.0: vedquota(8), vncheck(8), vquot(8), vquota(1), vquotaon(8), vquotaoff(8), and vrepquota(8). The operations supported by these retiring commands are also supported by
the following commands edquota(8), ncheck(8), quot(8), quota(1), quotaon(8), quotaoff(8), and repquota(8). The
POLYCENTER Advanced File System Utilities are licensed separately from the DIGITAL UNIX operating system
and must be purchased separately. Both the software and the reference pages are contained in the separatelylicensed product, and must be installed before being used. The following list summarizes the POLYCENTER Advanced File System Utilities commands:
Adds a volume to an existing file domain. See addvol(8). Starts the AdvFS graphical user interface (GUI) daemon.
Balances the percentage of used space between volumes. See balance(8).
Creates a read-only copy of a fileset. See clonefset(8). Makes the files in a file domain more contiguous. See defragment(8).
Starts the AdvFS graphical user interface. See dtadvfs(8). Moves the location of a file within a file domain. See
migrate(8).
Attaches directories to a trashcan directory, which stores deleted files. See mktrashcan(8). Detaches a specified directory from a trashcan directory. See mktrashcan(8).
Removes a volume from an existing file domain. See rmvol(8). Shows the trashcan directory, if any, that is attached
to a specified directory. See mktrashcan(8).
Interleaves storage allocation of a file across two or more volumes within a file domain. See stripe(8). When configuring root on AdvFS, set up one partition and one fileset in the file domain. Multiple volumes are not supported
on root. The following example creates a file domain called accounts_dmn, which contains rz1c as the initial volume. The example also creates two filesets, credit_fs and debit_fs and mounts both filesets.
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mkfdmn /dev/rz1c accounts_dmn
mkfset accounts_dmn credit_fs
mkfset accounts_dmn debit_fs
mkdir /mnt/credit /mnt/debit
mount -t advfs accounts_dmn#credit_fs /mnt/credit
mount -t advfs accounts_dmn#debit_fs /mnt/debit
advfs_err(4), fdmns(4), mkfdmn(8), mkfset(8), mkdir(1), mount(8). delim off