Go to main content

man pages section 8: System Administration Commands

Exit Print View

Updated: Wednesday, July 27, 2022



metasync - handle metadevice resync during reboot


/usr/sbin/metasync -h
/usr/sbin/metasync [-s setname] [buffer_size] metadevice
/usr/sbin/metasync [-s setname] -r [buffer_size]
/usr/sbin/metasync -p metadevice
/usr/sbin/metasync -c metadevice


The metasync command starts a resync operation on the specified metadevice. All components that need to be resynced are resynced. If the system crashes during a RAID5 initialization, or during a RAID5 resync, either an initialization or resync restarts when the system reboots.

Applications are free to access a metadevice at the same time that it is being resynced by metasync. Also, metasync performs the copy operations from inside the kernel, which makes the utility more efficient.

Use the –r option in boot scripts to resync all possible submirrors.


The following options are supported:

–c metadevice

Cancels the resync that is in progress on the specified metadevice. The resync will be stopped at its current point and can be resumed by running the “metasync metadevice” command. This option only applies to RAID1 volumes.


Displays usage message.

–p metadevice

Regenerates parity information for RAID5 metadevices.

–s setname

Specifies the name of the diskset on which metasync will work. Using the –s option will cause the command to perform its administrative function within the specified diskset. Without this option, the command will perform its function on local metadevices.


Specifies that the metasync command handle special resync requirements during a system reboot. metasync –r should only be invoked from the svc:/system/mdmonitor service. The metasync command only resyncs those metadevices that need to be resynced. metasync schedules all the mirror resyncs according to their pass numbers.

To override the default buffer_size value used by the svc:/system/mdmonitor service, you can edit /etc/system to specify:

set md_mirror:md_resync_bufsz = 2048

so that resyncs occur as quickly as possible.



Specifies the size (number of 512-byte disk blocks) of the internal copy buffer for the mirror resync. The size defaults to 1024 512-byte disk blocks. It can be no more than 2048 blocks. For best performance (quickest completion of the resync), 2048 blocks is the recommended size.

Exit Status

The following exit values are returned:


Successful completion.


An error occurred.


See attributes(7) for descriptions of the following attributes:


See Also

md(4D), md.cf(5), md.tab(5), md.tab(5), mddb.cf(5), attributes(7), metattach(8), mdmonitord(8), metaclear(8), metadb(8), metadetach(8), metahs(8), metainit(8), metaoffline(8), metaonline(8), metaparam(8), metarecover(8), metarename(8), metareplace(8), metaset(8), metassist(8), metastat(8)


The metasync service is managed by the service management facility, smf(7), under the service identifier:


Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(8). The service's status can be queried using the svcs(1) command.