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defragment(8) System Manager's Manual defragment(8) NAME defragment - Makes the files in a file domain more contiguous SYNOPSIS /usr/sbin/defragment [-e] [-n] [-t time] [-T time] [-v] [-V] domain PARAMETERS Specifies the name of the file domain. FLAGS Ignores errors and continues, if possible. Errors that are ignored are usually related to a specific file. Prevents defragmentation from ac- tually taking place. Use in conjunction with the -v flag to display statistics on the number of extents in the file domain. Specifies a flexible time interval (in minutes) for the defragment utility to run. If the utility is performing an operation when the specified time has elapsed, the procedure continues until the operation is complete. Specifies an exact time interval (in minutes) for the defragment util- ity to run. When the specified time has elapsed, the defragmentation procedure stops, even if it is performing an operation. Displays sta- tistics on the amount of fragmentation in the file domain and informa- tion on the progress of the defragment procedure. Displays the same information provided by the -v flag along with information about each operation the defragment utility performs on each file. This flag slows the defragment procedure. DESCRIPTION When a file consists of many discontiguous file extents, the file is fragmented on the disk. File fragmentation reduces the read/write per- formance because more I/O operations are required to access a frag- mented file. The defragment utility attempts to reduce the number of file extents in a file domain by making files more contiguous. Defragmenting a file domain often makes the free space on a disk more contiguous, resulting in less fragmented file allocations in the future. Before you can defragment a file domain, all filesets in the file do- main must be mounted. If you try to defragment an active file domain that includes unmounted filesets, the system displays an error message indicating that a fileset is unmounted. To determine the amount of file fragmentation in a file domain before using the defragment utility, issue the defragment command with the -v and -n flags. This provides the fragmentation information without starting the defragment utility. Before running the defragment utility, delete any files in the domain that you do not need. This gives the defragment utility more free space to use, which produces better results. Deleting files afterwards cre- ates more free-space fragments. To monitor the improvement made to the file domain by the defragment utility, use the verbose mode flag, -v, which displays the following information: Extents The number of extents in the specified domain. (Contiguous ex- tents in sparse files are counted as one extent after defragmentation, when in fact there are several contiguous file extents.) Files w/ ex- tents The number of files that have extents. (Note that files do not have extents if the files are so small that they are kept with the metadata.) Avg exts per file w/ exts The average number of extents for each file that has one or more extents. Aggregate I/O perf The effi- ciency of the entire file domain. An increase in value indicates im- provement. Free space fragments The number of free-space fragments in the domain. RESTRICTIONS The defragment utility requires a minimum of 1 percent of the total space, or 5 megabytes per volume (whichever is less) to be free in or- der to run. The defragment utility does not defragment striped files. You cannot run the defragment utility while the addvol, balance, de- fragment, rmfset, or rmvol utility is running on the same file domain. You must be the root user to use this utility. EXAMPLES The following example defragments the file domain called accounts_dmn. A flexible time limit of 15 minutes is imposed and verbose mode is re- quested to display the fragmentation data: # defragment -v -t 15 accounts_dmn defragment: defragmenting domain 'accounts_dmn' Pass 1; Clearing Volume 1: area at block 11680 ( 103072 blocks): 81% full Domain data as of the start of this pass: Extents: 10432 Files w/extents: 4305 Avg exts per file w/exts: 2.42 Aggregate I/O perf: 52% Free space fragments: 2743 <100K <1M <10M >10M Free space: 38% 0% 0% 62% Fragments: 2742 0 0 1 Filling . . . Pass 13; Clearing Volume 1: area at block 559744 ( 62736 blocks): 0% full Volume 2: area at block 76640 ( 24624 blocks): 18% full Domain data as of the start of this pass: Extents: 4306 Files w/extents: 4305 Avg exts per file w/exts: 1.00 Aggregate I/O perf: 100% Free space fragments: 23 <100K <1M <10M >10M Free space: 0% 9% 27% 64% Fragments: 6 10 5 2 Filling Current domain data: Extents: 4305 Files w/extents: 4305 Avg exts per file w/exts: 1.00 Aggregate I/O perf: 100% Free space fragments: 17 <100K <1M <10M >10M Free space: 0% 6% 29% 65% Fragments: 3 8 4 2 defragment: defragmented domain 'accounts_dmn' The information dis- played before each pass and at the conclusion of the defragmentation process shows the improvement made to the file domain by the defragment utility. RELATED INFORMATION addvol(8), balance(8), rmvol(8). delim off defragment(8)