IBM N Series Hardware Manual page 133

Read performance is optimized by performing application reads from both plexes as shown in
Figure 8-9.
Figure 8-9 Synchronous mirroring
SyncMirror is used to create aggregate mirrors. When planning for SyncMirror environments,
keep in mind the following considerations:
Aggregate mirrors need to be on the remote site (geographically separated)
In normal mode (no takeover), aggregate mirrors cannot be served out
Aggregate mirrors can exist only between like drive types.
When the SyncMirror license is installed, disks are divided into pools (pool0: local, pool1:
remote/mirror). When a mirror is created, Data ONTAP pulls disks from pool0 for the local
aggregate and from pool1 for the mirrored aggregate. Verify the correct number of disks in
each pool before creating the aggregates. Any of the following commands can be used as
shown in Example 8-1.
Example 8-1 Verification of SyncMirror
itsosj_n1>sysconfig -r
itsosj_n1>aggr status -r
itsosj_n1>vol status -r
To see the volume /plex/raidgroup relationship, use the sysconfig –r command as shown in
Example 8-2. Use the aggr mirror command to start mirroring the plexes.
Example 8-2 Viewing the aggregate status
n5500-ctr-tic-1> sysconfig -r
Aggregate aggr0 (online, raid_dp, mirrored) (block checksums)
Plex /aggr0/plex0 (online, normal, active, pool0)
RAID group /aggr0/plex0/rg0 (normal)
RAID Disk Device HA SHELF BAY CHAN Pool Type RPM Used (MB/blks)
--------- ------ ------------- ---- ---- ---- ----- --------------
dparity 0a.16
parity 0a.17
data 0a.18
Plex /aggr0/plex2 (online, normal, active, pool1)
0a 1 0 FC:A 0 FCAL 15000 136000/278528000 137104/280790184
0a 1 1 FC:A 0 FCAL 15000 136000/278528000 137104/280790184
0a 1 2 FC:A 0 FCAL 15000 136000/278528000 137104/280790184
Phys (MB/blks)
--------------
Chapter 8. MetroCluster
113