sg_sync man page

sg_sync — send SCSI SYNCHRONIZE CACHE command


sg_sync [--16] [--count=COUNT] [--group=GN] [--help] [--immed] [--lba=LBA] [--sync-nv] [--timeout=SECS] [--verbose] [--version] DEVICE


Send SYNCHRONIZE CACHE(10) or SYNCHRONIZE CACHE(16) command to DEVICE. These commands are defined for SCSI block devices (see SBC-3). If successful these commands make sure that any blocks whose latest versions are held in cache are written to (also termed as "synchronized with") the medium.

If the LBA and COUNT arguments are both zero (their defaults) then all blocks in the cache are synchronized. If LBA is greater than zero while COUNT is zero then blocks in the cache whose addresses are from and including LBA to the highest lba on the device are synchronized. If both LBA and COUNT are non zero then blocks in the cache whose addresses lie in the range LBA to LBA+COUNT-1 inclusive are synchronized with the medium.


Arguments to long options are mandatory for short options as well.

-S, --16

performs a SYNCHRONIZE CACHE(16) command. Default is to perform a SYNCHRONIZE CACHE(10) command.

-c, --count=COUNT

where COUNT is the number of blocks to synchronize from and including LBA. Default value is 0. When 0 then all blocks in the cache from and including LBA argument to the highest block address are synchronized.

-g, --group=GN

where GN is the group number which can be between 0 and 31 inclusive. The default value is 0 . Group numbers are used to segregate data collected within the device. This is a new feature in SBC-2 and can probably be ignored for the time being.

-h, --help

output the usage message then exit.

-i, --immed

sets the IMMED bit in the SYNCHRONIZE CACHE command. This instructs the device, if the format of the command is acceptable, to return a GOOD status immediately rather than wait for the blocks in the cache to be synchronized with (i.e. written to) the medium.

-l, --lba=LBA

where LBA is the lowest logical block address in the cache to synchronize to the medium. Default value is 0 .

-s, --sync-nv

synchronize the (volatile) cache with the non-volatile cache. Without this option (or if there is no non-volatile cache in the device) the synchronization is with the medium. The SYNC_NV bit was made obsolete in SBC-3 revision 35d.

-t, --timeout=SECS

where SECS is the number of seconds the OS allows the SYNCHRONIZE CACHE(16) to complete before it tries to cancel the command. Cancelling commands (typically with the task management function "abort task") is best avoided. Note this option is only active together with the --16 option. The default timeout is 60 seconds for both SYNCHRONIZE CACHE(10) and SYNCHRONIZE CACHE(16). Note that timeout issues can be avoided with the --immed option.

-v, --verbose

increase the level of verbosity, (i.e. debug output).

-V, --version

print the version string and then exit.


With the SYNCHRONIZE CACHE(16) command LBA can be up to 64 bits in size and COUNT up to 32 bits in size. With the SYNCHRONIZ CACHE(10) command LBA can be up to 32 bits in size and COUNT up to 16 bits in size.

Various numeric arguments (e.g. LBA) may include multiplicative suffixes or be given in hexadecimal. See the "NUMERIC ARGUMENTS" section in the sg3_utils(8) man page.

Exit Status

The exit status of sg_sync is 0 when it is successful. Otherwise see the sg3_utils(8) man page.


Written by Douglas Gilbert.

Reporting Bugs

Report bugs to <dgilbert at interlog dot com>.

See Also



July 2013 sg3_utils-1.37 SG3_UTILS