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advfs(4) Kernel Interfaces Manual advfs(4) NAME advfs - A local file system and utilities DESCRIPTION The File System (AdvFS), a file system option on the DIGITAL UNIX oper- ating 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 op- erating system and is available as file system option during installa- tion. A set of utilities that expands the capabilities of the AdvFS file sys- tem is available: The 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 on- line backup, and improving system performance with domain balancing, and file striping. Additionally, a graphical user interface (GUI) that simplifies file system management is available with the utilities. The 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 fea- tures 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 file- sets can span all volumes in the file domain. AdvFS introduces file system concepts that do not exist for UFS. Un- derstanding 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 spec- ify a domain name and one initial volume. The mkfdmn command creates a subdirectory in the /etc/fdmns directory for each new file domain. The file-domain subdirectory contains a symbolic link to the initial vol- ume. 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 re- main 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 par- titions 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). Makes the files in a file domain more contiguous. See defragment(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 mkf- set(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 direc- tory. See vtagpg(8). Operations supported by the following AdvFS com- mands 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 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 separately- licensed product, and must be installed before being used. The follow- ing list summarizes the 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). 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 vol- ume from an existing file domain. See rmvol(8). Shows the trashcan di- rectory, if any, that is attached to a specified directory. See mk- trashcan(8). Interleaves storage allocation of a file across two or more volumes within a file domain. See stripe(8). RESTRICTION When configuring root on AdvFS, set up one partition and one fileset in the file domain. Multiple volumes are not supported on root. EXAMPLE The following example creates a file domain called accounts_dmn, which contains rz1c as the initial volume. The example also creates two file- sets, credit_fs and debit_fs and mounts both filesets. # mkfdmn /dev/rz1c accounts_dmn # mkfset accounts_dmn credit_fs # mkf- set accounts_dmn debit_fs # mkdir /mnt/credit /mnt/debit # mount -t ad- vfs accounts_dmn#credit_fs /mnt/credit # mount -t advfs ac- counts_dmn#debit_fs /mnt/debit RELATED INFORMATION advfs_err(4), fdmns(4), mkfdmn(8), mkfset(8), mkdir(1), mount(8). de- lim off advfs(4)