sndradm(1M) System Administration Commands sndradm(1M)NAMEsndradm - control Sun StorageTek Availability Suite Remote Mirror oper‐
ations
SYNOPSISsndradm-I a master shadow bitmap
sndradm-I d master shadow bitmap
sndradm-h usage message
sndradm-v version information
sndradm [options] -e [sndr_set]
sndradm [options] -E [sndr_set]
sndradm [options] -d [sndr_set]
sndradm [options] -D block [sndr_set]
sndradm [options] -D noblock [sndr_set]
sndradm [options] -l [sndr_set]
sndradm [options] -m [sndr_set]
sndradm [options] -m -r [sndr_set]
sndradm [options] -u [sndr_set]
sndradm [options] -u -r [sndr_set]
sndradm [options] -w [sndr_set]
sndradm [options] -H [sndr_set]
sndradm [options] -p [sndr_set]
sndradm [options] -P [sndr_set]
sndradm [options] -q a volume [sndr_set]
sndradm [options] -q d [sndr_set]
sndradm [options] -q r volume [sndr_set]
sndradm [options] -i [sndr_set]
sndradm [options] -a value [sndr_set]
sndradm [options] -A value [sndr_set]
sndradm [options] -F value [sndr_set]
sndradm [options] -W value [sndr_set]
sndradm [options] -R
sndradm [options] -R b p bitmap [sndr_set]
sndradm [options] -R b s bitmap [sndr_set]
sndradm [options] -R C tag [sndr_set]
sndradm [options] -R g io_groupname [sndr_set]
sndradm [options] -R m sync [sndr_set]
sndradm [options] -R m async [sndr_set]
sndradm [options] -R -f volset-file
sndradm [options] -R r [sndr_set] *
DESCRIPTION
The /usr/sbin/sndradm command is the administrative command line inter‐
face for the Sun StorageTek Availability Suite Remote Mirror software.
Remote Mirror enables you to replicate disks between different physi‐
cally-separate Sun servers in real time. Remote Mirror is conceptually
similar to the local disk mirroring scheme of RAID 1 but it performs
its replication operations over longer distances.
If you do not specify a Remote Mirror set (sndr_set) on the command
line, sndradm operates on all configured Remote Mirror sets.
The sndradm command generates an entry in the Availability Suite log
file, /var/adm/ds.log (see ds.log(4)), for all operations except print
(-p, -P and -i), help (-h), and version (-v).
OPTIONS
The sndradm utility supports the following options:
-f volset-file
Specifies a file containing the sndr_set information for one or
more Remote Mirror sets in the same format as the fully specified
command line sndr_set documented below.
-g io_groupname
Limits operations to only those Remote Mirror sets belonging to
io_groupname.
The io_groupname for a given set must be consistent across both the
primary and the secondary hosts.
-C tag
On a clustered node, limits operations to only those Remote Mirror
sets belonging to the cluster resource group or disk group name
specified by tag. This option is not valid on a system that is not
clustered.
-n
Does not prompt the user after starting a Remote Mirror operation
using sndradm. For all but the printing, help, and version options,
the default behavior is to prompt for a response. For example,
after starting a full synchronization from the primary to the sec‐
ondary volume, Remote Mirror prompts: "Overwrite secondary with
primary? (Y/N) [N]".
sndr_set
Specifies the Remote Mirror set. For a set that has already been
enabled, this can be a set_name in the format shost:sdev. You can
supply a fully specified Remote Mirror set in the same format as a
configuration file:
phost pdev pbitmap shost sdev sbitmap ip {sync | async} \
[g io_groupname] [C tag]
These parameters are described as follows:
phost
Specifies the server on which the primary volume resides.
pdev
Specifies the primary volume partition to be replicated. Spec‐
ify full pathnames only (for example, /dev/rdsk/c0t1d0s2).
pbitmap
Specifies the volume partition on which the bitmap (scoreboard
log) of the primary partition is stored. Specify full pathnames
only (for example, /dev/rdsk/c0t1d0s3).
shost
Specifies the server on which the secondary volume resides.
sdev
Specifies the secondary volume partition. Specify full path
names only (for example, /dev/rdsk/c0t1d0s4).
sbitmap
Specifies the volume partition on which the bitmap (scoreboard
log) of the secondary partition is stored. Specify full path
names only (for example, /dev/rdsk/c0t1d0s5).
ip
Specifies the network transfer protocol.
sync | async
Specifies the Remote Mirror operating mode. sync is the Remote
Mirror mode where the I/O operation is not confirmed as com‐
plete until the remote volume has been updated. async is the
Remote Mirror mode where the primary host I/O operation is con‐
firmed as complete before updating the remote volume.
io_groupname
Specifies the name of the Remote Mirror consistency group to
which the Remote Mirror set belongs. In asynchronous mode,
write ordering must be preserved across all replicating volumes
in a Remote Mirror consistency group. This ensures that the
secondary volumes belonging to the group contains a valid
point-in-time copy of the corresponding primary volumes.
When adding an existing set to a consistency group or when
enabling a set to be in a group, the set must be configured
with the same group name on both the primary and the secondary
hosts.
tag
For operation within a cluster, this specifies the disk group
name or resource tag of the local data and bitmap volumes in
cases where this is not implied by the name of the volume (for
example, /dev/rdsk/md/dg/vol and /dev/vx/rdsk/dg/vol both indi‐
cate a disk group name of dg). It is the responsibility of the
user to ensure that the cluster tag specified to the Remote
Mirror matches the appropriate cluster resource group tag, and
to keep all the Availability Suite services up to date in the
event of cluster resource group reconfigurations. It is illegal
to specify the cluster resource tag on a system that is not
clustered.
PARAMETERS
A valid sndradm command must specify one of the parameters listed
below.
-I a master shadow bitmap
Add an ndr_ii entry with the specified master, shadow, and bitmap
to the Availability Suite configuration file. See sndrsyncd(1M). If
the corresponding Point-in-Time Copy set does not exist, it is
enabled when the next sync command is issued on the related vol‐
ume(s). When no longer required, this Point-in-Time Copy set can be
disabled by iiadm -d. See iiadm(1M)-I d master shadow bitmap
Delete the ndr_ii entry with the specified master, shadow, and bit‐
map from the Availability Suite configuration file. Use the dscfg
command to list ndr_ii configuration entries.
-a value
Specifies the value, on or off, of the automatic sync variable for
the set. Once autosync has been requested for a set, the function‐
ality is active from the time a sync operation is requested until
the set is manually put into logging mode. Once the set is manually
put into logging mode, the autosync functionality is not active and
remains inactive until the next time a sync request is made. To
check whether autosync is active, use sndradm-P. To check whether
autosync has been requested for a set, look for the"auto=on;" tag
for the set in the output of dscfg -l. See sndrsyncd(1M).
-A value
Specifies the maximum number of threads that can be created to
process the asynchronous queue when a set is replicating in asyn‐
chronous mode. The default is 2.
-W value
Specifies the maximum number of writes that can be queued to a set
replicating in asynchronous mode. The default is 4096. For example,
set this value to 1 to ensure that the secondary volume is never
more than one write operation behind the primary volume.
Tuning the maximum number of writes is only valid for sets using
memory-based async I/O queues. This value is ignored when disk
based I/O queues are used.
-D {block | noblock}
Toggles the block|noblock attribute of a disk-based queue. The
default setting is block. If the I/O fill rate is larger than the
drain rate for enough time for the queue to fill, incoming I/O is
blocked until there is adequate space on the queue for it. This is
to preserve write ordering whether it is one volume or across many
volumes in the same consistency group. If noblock is set, and
incoming I/O fills the queue, the I/O is not blocked. Instead, the
set is put into logging and the disk queue contents are disre‐
garded. An ensuing update sync synchronizes the latest data to the
secondary site.
-F value
Specifies the maximum number of 512-byte FBAs that can be queued in
kernel memory to a set replicating in asynchronous mode. The
default is 16384.
Tuning the maximum number of FBAs is valid only for sets using mem‐
ory-based async I/O queues. This value isignored when disk-based
I/O queues are used.
-h
Prints the sndradm usage summary.
-v
Prints the Remote Mirror version number.
-e
Enables Remote Mirror for the set and enables scoreboard logging.
The scoreboard is set to indicate that a full synchronization is
required. Details of the set are saved in the current configura‐
tion. See dscfg(1M). The local volume and the bitmap volume are
enabled for the Storage Volume driver (see sv(7D)).
-E
Enables Remote Mirror for the set and enables scoreboard logging.
The scoreboard is cleared to indicate that the primary and sec‐
ondary volumes are already guaranteed to be fully synchronized.
Details of the set are saved in the current configuration. See
dscfg(1M). The local volume and the bitmap volume are enabled for
the Storage Volume driver (see sv(7D)).
-d
Disables Remote Mirror for the set and halts any current synchro‐
nization operations. sndradm-d also discards any active score‐
boards that track temporary differences between primary and sec‐
ondary volumes.
-l
Stops Remote Mirror replication and copy operations between primary
and secondary volumes and starts independent Remote Mirror score‐
board logging on these volumes. When all the sets in a consistency
group are replicating, it means that the secondary volumes contain
a valid point-in-time copy of the corresponding primary volumes.
Under this condition, as soon as one Remote Mirror set drops into
logging mode, the rdc kernel module drops all the other sets in the
group into logging mode automatically. This ensures that the sec‐
ondary volumes still contains a valid point-in-time copy. To resume
the Remote Mirror after using the -l parameter, use the -m parame‐
ter to perform a full resynchronization or the -u parameter to per‐
form an update resynchronization (based on the scoreboard).
This option does not work on the secondary for any volumes that are
currently synchronizing.
-w
Waits for a synchronization copy to complete or abort, or returns
immediately if invoked on the secondary system.
-H
Reports on the health of the network link used by the specified
volume set. The health of the link is reported as active or inac‐
tive. Active means that the network link is actively being used for
replicating or resynchronizing data, and is therefore in good
health. Inactive means that the network link is not actively being
used for replicating or resynchronizing data, which might indicate
a problem with the link.
-p
Displays a list of configured Remote Mirror volumes or sets.
-P
Displays a list of configured Remote Mirror volumes or sets with
extra details. (See state descriptions, below.)
-q a volume
Add a disk queue to a set or group. This operation is valid when
the set or group is in logging mode.
-q d
Remove a disk queue from a set or group. This operation is valid
when the set or group is in logging mode.
-q r volume
Replace a disk queue for a group or set. The queue is removed from
the set or group as in the queue-disable operation and the new disk
queue is added as in the queue-add operation. This operation is
valid when the set or group is in logging mode.
-i
Displays a list of configured Remote Mirror volumes or sets in the
same format as the volset-file.
-R
Attempt to reset a Remote Mirror set's error condition such as
failed bitmaps.
-R b p bitmap
Reconfigure a Remote Mirror set's primary bitmap. This command
should be entered on both primary and secondary servers. It is only
possible to reconfigure the primary bitmap for one set at a time.
-R b s bitmap
Reconfigure a Remote Mirror set's secondary bitmap. This command
should be entered on both primary and secondary servers. It is only
possible to reconfigure the secondary bitmap for one set at a time.
-R C tag
Reconfigure the cluster tag, or disk group name, of a Remote Mirror
set's local volumes, in those cases where this is not indicated by
the pathname. This does not affect the remote volumes. This parame‐
ter cannot be used on a system that is not clustered.
-R m {sync | async}
Reconfigure the replication mode of a Remote Mirror set. The sets
belonging to a consistency group must be either all synchronous or
all asynchronous. It is not possible to mix modes within a group.
-R g group
Reconfigure the consistency group of a Remote Mirror set. This com‐
mand should be entered with the same group name on both primary and
secondary servers.
To remove a set from a consistency group, specify the null string
(" ") when reconfiguring the consistency group.
The following parameters can be issued only from the primary server:
-m
Starts a full volume copy from the primary volume to the secondary
volume, and concurrently enables Remote Mirror replication of new
updates from the primary volume to the secondary volume. Use this
parameter when the primary and secondary volumes might be different
and no logging information exists to incrementally resynchronize
the volumes. See EXIT STATUS.
-r
Reverses the direction of the synchronization so the primary volume
is synchronized from the secondary volume. Use this parameter with
the -m or -u parameter. -m -r starts a full volume copy from the
secondary (source) volume to the primary (target) volume but con‐
currently enables Remote Mirror replication of new updates from the
primary (source) volume to the secondary (target) volume, ensuring
the volume sets remain synchronized. Use -m -r when the primary and
secondary volume content might differ and the secondary has the
desired contents, yet no logging information exists to incremen‐
tally resynchronize the volumes (using -u). -u-r resynchronizes
the primary (target) volume from the secondary (source) volume,
using the Remote Mirror scoreboard logs maintained while replica‐
tion was suspended. It then resumes Remote Mirror replication of
new updates from the primary volume to the secondary volume so that
the volume sets remain synchronized. Quiesce the workload to the
volume sets during the restore/refresh operation. This action
ensures that the primary and secondary volumes match before repli‐
cation of new updates resumes.
-u
Updates a Remote Mirror volume set. This parameter resynchronizes a
Remote Mirror volume set. Only the blocks logged as changed in the
Remote Mirror scoreboards are updated. Enables Remote Mirror repli‐
cation for the primary volume and also uses the Remote Mirror
scoreboard logs to start the resynchronization process so that the
corresponding secondary volume matches the primary volume.
States Returned from sndradm-P
The following are the states that can be returned from sndradm-P.
volume failed
An I/O operation to the local data volume has failed
bitmap failed
An I/O operation to the local bitmap volume has failed
disk queue failed
An I/O operation to disk queue volume has failed
need sync
A sync to this volume has been interrupted. It needs to be com‐
pleted (or restored via Point-in-Time Copy). The direction of the
data flow must not be changed until one or the other is done.
need reverse sync
A reverse sync to this volume has been interrupted. It needs to be
completed (or restored via Point-in-Time Copy). The direction of
the data flow must not be changed until one or the other is done.
logging
Incoming writes are logged in the bitmap only. Data is not repli‐
cated to the remote site. need sync, need reverse sync, and queuing
are all substates of logging such that writes are logged in the
bitmap, but not replicated. Queuing mode (described below) logs the
writes to the bitmap, and queues the request for later replication
by the async flushers.
reverse syncing
A secondary to primary copy is in progress.
syncing
A primary to secondary copy is in progress.
queuing
During normal async replication using disk queues, i/o is placed on
the disk queue to be replicated by the async flusher threads. In
the event of a temporary link failure, the set transitions to queu‐
ing mode. The queue is not discarded, as it would be with memory
based queues. Instead, data is logged in the bitmap and placed on
the queue. When the link comes up, and sndradm-u is issued, (auto‐
mated by turning autosync on for the set) the flushers restarts.
This preserves write ordering through a temporary link outage. If
write ordering is not necessary, and only the latest data is
needed, the set can be put into logging manually (sndradm -l) and
an update sync issued (sndradm -u). This action discards the data
on the queue, and fast resyncs using the bitmap. If the queue fills
before the link comes back and the update sync is issued, the queue
is discarded and the set put into logging mode to avoid application
hangs.
EXAMPLES
Example 1 Enabling a Remote Mirror Set
The following command enables a Remote Mirror asynchronous set on host
example, where example is the primary host and example-remote is the
secondary host.
example% sndradm-e example /dev/rdsk/c1t0d0s1 /dev/rdsk/c1t1d0s3 \
example-remote /dev/rdsk/c2t3d0s5 /dev/rdsk/c2t4d0s5 ip async
Example 2 Adding a Disk Queue to an Asynchronous Set
The following command adds a disk queue volume to an asynchronous set.
example% sndradm-q a /dev/rdsk/c1t2d0s3 \
example-remote:/dev/rdsk/c2t3d0s5
Example 3 Removing a Disk Queue from an Asynchronous Set
The following command removes the disk queue volume from a set with a
disk queue volume attatched to it.
example% sndradm-q d example-remote:/dev/rdsk/c2t3d0s5
Example 4 Disabling a Remote Mirror Set
The following command disables a Remote Mirror set enabled on host
example.
example% sndradm-d example-remote:/dev/rdsk/c2t3d0s5
EXIT STATUS
0 Command completed successfully.
>0 An error occurred.
When the -m or -u option is executed in a script, the exit status fol‐
lowing one of these options always returns success, regardless of the
current status of the Remote Mirror set.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │storage/avs/remote-mirror, │
│ │storage/avs/remote-mirror │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOdscfg(1M), sndrd(1M), sndrsyncd(1M), ds.log(4), rdc.cf(4),
attributes(5), sv(7D)SunOS 5.11 2 Oct 2007 sndradm(1M)
