vfast - Runs the vfast utility in the background to reduce
file fragmentation, and to balance volume free space and
I/O load.
/sbin/advfs/vfast [activate | deactivate | suspend |status]
domain
/sbin/advfs/vfast [-l | -L {-extents | -hotfiles }] domain
/sbin/advfs/vfast -o option_list domain
The vfast utility has control, display, processing and
configuration options.
The following are control options: Activates vfast operation
on the domain. Deactivates all vfast operation on
the domain and stops gathering any internal statistics.
This is the default. Displays the current vfast configuration,
operational statistics, and processing options for
the domain. Temporarily disables all vfast option processing
on the domain but continues to gather internal
statistics. Displays extents and hotfiles (most actively
paging files) for a volume and domain. Displays the files
currently queued for defragmentation and volume free space
balancing. Displays the most actively paging files and
the volumes on which they reside. Displays extent and
hotfile (most actively paging files) summary statistics
for a domain. Displays fragmentation summaries by volume.
Displays a distribution summary by volume and domain of
the most actively paging files. Allows you to change one
or more processing options or processing configurations by
specifying a comma-separated list. Equalizes free space
across all volumes in a domain by moving fragmented files
between volumes. Enables free space balancing on the
domain. The defragment= option must be enabled. Disables
free space balancing on the domain. This is the default.
Consolidates file extents on the domain. Enables file
defragmentation on the domain. Disables file defragmentation
on the domain. This is the default. Distributes
files with high I/O among volumes to improve I/O throughput.
Enables volume I/O load balancing on the domain.
Does not perform volume I/O load balancing. This is the
default. Manages vfast effects on files that are currently
enabled for direct I/O. Allows vfast to defragment
files that are using direct I/O. This is the default.
Prevents vfast from defragmenting files that are using
direct I/O. Specifies the number of hours from the first
writable fileset mount to the start of top I/O balancing.
Limits the share of system I/O that -vfast uses to a maximum
of the percent specified. However, most vfast processing
occurs when devices have no other system I/O. The
default is 1 percent. The high limit for percent_ios_when_busy=
is 50 percent.
Specifies the domain name.
The vfast utility runs at the operating system level with
low overhead, continuously defragmenting and balancing
files, consolidating free space and distributing the file
I/O over the volumes of a domain. It only processes files
that are actively being opened and closed. The utility
automatically runs during periods of low system demand so
that system administrators do not have to take a system
off line.
The vfast utility balances the available free space over
volumes to maximize file-creation performance. It defragments
all active files including the frag file and the
root tag file. The system administrator does not need to
perform balance and defragment maintenance tasks. The
utility also uses file I/O statistics gathered by the
AdvFS kernel to distribute files with high I/O to different
volumes in the domain
The vfast utility takes into account reserved file access,
but it does not move any of the reserved files.
Files or filesets with direct I/O enabled might be moved
when consolidating free space.
The features of vfast that are in effect and the system
activity that occurs from running the command are displayed
by the vfast -status option for the specified
domain: Defragment
Consolidation of free space. Balance
Distribution of files to different volumes. TopIObalance
Continuous distribution of files with high I/O to
different volumes. Direct I/O File Processing
Processing files that have direct I/O enabled.
Percent IOs Allocated to vfast when System Busy
Controls the utility's access to system resources.
Default Hours until Steady State
Time that must elapse while the system collects
statistics before I/O balancing operations start.
Total Files Defragmented
The number of files that have been moved to more
contiguous locations on disk. Total Pages Moved
for Defragment
The number of pages that were moved to more contiguous
locations on disk. Total Extents Combined
for Defragment
The number of file extents that were consolidated.
Total Pages Moved for Balance
The number of pages that were moved to equalize
free space on the volumes of the domain. Total
Files Moved for Volume IO Balance
The number of files that were moved to equalize I/O
load on the volumes of the domain. Total Pages
Moved for Volume Free Space Consolidation
The number of pages that were moved to create contiguous
space on the volumes of the domain.
The vfast -l command displays the following information
about the specified domain by volume: Extent Count
Number of extents per file. Files that are less
than 8 kilobytes have no extents. Fileset / File
Name of filesets and files with extents.
The vfast -L command displays the information of the vfast
-l command and also: Average Extents per File with Extents
The average number of extents for each file that
has one or more extents. Free Space Fragments
The number of free space fragments. Free Space
The percentage of fragments by size. Fragments
The number of fragments by size.
Do not enable topIObalance= if your domain has multiple
volumes created on the same disk. The utility cannot
effectively distribute the I/O load because there is only
one I/O bus.
Do not enable topIObalance= if your domain is composed of
LSM striped volumes or LSM volumes that are a concatenation
of partitions from multiple storage devices or partitions.
Also disable this option when using RAID devices
with striping enabled. The utility cannot effectively distribute
the I/O load.
If vfast is activated and defragment=, balance=, or topIObalance=
are enabled on a domain, then the standard AdvFS
balance and defragment utilities are not available.
If direct_io= is enabled, files enabled with direct IO are
not evaluated for top I/O balance because I/O on these
files bypasses vfast statistics collection. However, they
can still be moved by vfast when free space is consolidated
to make room for files being defragmented.
The vfast -o balance= operation is not enabled unless
defragment= is also enabled.
If you reboot or unmount all filesets in a given domain,
current file I/O histories are lost. It is possible to
temporarily suspend vfast processing and not lose the
internal statistics and files queued for defragmenting by
changing vfast to suspend mode. The standard AdvFS
defragment and balance utilities can be run while vfast is
in suspend or deactivate mode.
If a system node is a cluster member, some files may not
be processed initially because cluster file system (CFS)
caches files and processing cannot occur until the cache
is flushed.
The following example changes the processing options: #
vfast -o defragment=enable,balance=enable,topIObalance=enable
q_domain
# vfast status q_domain
vfast is currently running
vfast is activated on q_domain
vfast defragment: enabled
vfast balance: enabled
vfast top IO balance: enabled Options:
Direct IO File Processing: enabled
Percent IOs Allocated to vfast When System Busy: 1%
Default Hours Until Steady State: 24; Hours remaining: 0
Total Files Defragmented: 44208
Total Pages Moved for Defragment: 5873696
Total Extents Combined for Defragment: 12212
Total Pages Moved for Balance: 248266
Total Files Moved for Volume IO Balance: 1
Total Pages Moved for Volume Free Space Consolidation:
914
The following example summarizes the extents by volume for
the domain x_domain: # vfast -l extents x_domain
x_domain: Volume 1
extent count fileset/file
No extents
x_domain: Volume 2
extent count fileset/file
5 foo: /qfoo/sub1/sub2/lockf
32 foo: /qfoo/sub1/sub2/tmp.vmunix.cp0
x_domain: Volume 3
extent count fileset/file
5 foo: /qfoo1/sub1/sub2/nvbmtpg.BSR_DMN_SS_ATTR
2 foo: /qfoo1/sub1/sub2/mount
10 foo: /qfoo1/sub1/sub2/quota.user
3 foo: /qfoo1/sub1/sub2/vfast
144 foo: /qfoo1/sub1/sub2/tmp.vmunix.cp1
140 foo: /qfoo1/sub1/sub2/tmp.vmunix.cp2
The following example displays extents for the files in
the domain usr_domain: # vfast -L extents usr_domain
usr_domain
Extents: 15745
Files w/extents: 9103
Avg exts per file w/exts: 1.73
Free space fragments: 2320
<100K <1M <10M> 10M
Free space: 2% 1% 2% 95%
Fragments: 2175 115 13 17
/sbin/advfs/vfast
Commands: defragment(8) , balance(8)
Files: advfs(4)
vfast(8)
[ Back ] | 