How to reestablish the SRDF relationship following a SRDF split operation
Article ID: 100037829
Updated On:
Description
Description
This document attempts to explain the steps required to reestablish the EMC SRDF relationship following a SRDF split operation when using Veritas Volume Manager (VxVM) and DMP.
EMC SRDF logically pairs a device or a group of devices from each array and replicates data from one to the other synchronously or asynchronously. An established pair of devices can be split, so that separate hosts can access the same data independently (maybe for backup), and then resynchronized.
In this instance, the configuration consists of "4" EMC SRDF "R1" devices presented to production server "Dopey" from EMC Symmetrix id (SID) "822". An additional "4" EMC SRDF "R2" devices have been presented to DR server "Bashful" from EMC Symmetrix ID (SID) "414".
In synchronous mode (SRDF/S), the primary array waits until the secondary array has acknowledged each write before the next write is accepted, ensuring that the replicated copy of the data is always as current as the primary. However, the latency due to propagation increases significantly with distance.
In asynchronous mode (SRDF/A) transfers the changes to the secondary array in units called delta sets, which are transferred at defined intervals. Although the remote copy of the data will never be as current as the primary copy, this method can replicate data over considerable distances and with reduced bandwidth requirements and mimimal impact on host performance.
Figure 1.0
Note: As of 5.0 MP3 onwards, the VxVM CLI command "vxdisk -e list" is capable of reporting the extended attribute based content for EMC BCV, BCV-NR, MIRROR, SRDF-R1, SRDF-R2, TDEV device states and EMC lun types.
Example
In this instance, the local EMC SYMDEVs are 008C, 008D, 008E and 008F. The remote EMC SYMDEVs are 0072, 0073, 0074 and 0075
The local VxVM Diskgroup named "DopeyDg" consists of four disks replicated to the remote host "Bashful".
a.] At this time, the SRDF relationship has been split, enabling the remote VxVM Diskgroup image to be imported on the remote host "Bashful".
Dopey # symrdf -g DopeyDg query
Device Group (DG) Name : DopeyDg
DG's Type : RDF1
DG's Symmetrix ID : 000290300822 (Microcode Version: 5773)
Remote Symmetrix ID : 000290301414 (Microcode Version: 5773)
RDF (RA) Group Number : 11 (0A)
Source (R1) View Target (R2) View MODES
-------------------------------- ------------------------ ----- ------------
ST LI ST
Standard A N A
Logical T R1 Inv R2 Inv K T R1 Inv R2 Inv RDF Pair
Device Dev E Tracks Tracks S Dev E Tracks Tracks MDA STATE
-------------------------------- -- ------------------------ ----- ------------
DEV08C 008C RW 0 4 NR 0072 RW 439 0 S.. Split
DEV08D 008D RW 0 0 NR 0073 RW 61 0 S.. Split
DEV08E 008E RW 0 0 NR 0074 RW 435 0 S.. Split
DEV08F 008F RW 0 0 NR 0075 RW 435 0 S.. Split
Total -------- -------- -------- --------
Track(s) 0 4 1370 0
MB(s) 0.0 0.2 85.6 0.0
Legend for MODES:
M(ode of Operation): A = Async, S = Sync, E = Semi-sync, C = Adaptive Copy
D(omino) : X = Enabled, . = Disabled
A(daptive Copy) : D = Disk Mode, W = WP Mode, . = ACp off
b.] The VxVM Diskgroup "DopeyDg" is imported on both the local and remote servers as independent images.
Local:
Dopey # vxdisk -eg DopeyDg list
DEVICE TYPE DISK GROUP STATUS OS_NATIVE_NAME ATTR
emc0_008c auto:cdsdisk r1-008C DopeyDg online c1t5006048C5368E580d266s2 srdf-r1
emc0_008d auto:cdsdisk r1-008D DopeyDg online c1t5006048C5368E5A0d223s2 srdf-r1
emc0_008e auto:cdsdisk r1-008E DopeyDg online c1t5006048C5368E5A0d229s2 srdf-r1
emc0_008f auto:cdsdisk r1-008f DopeyDg online c1t5006048C5368E580d269s2 srdf-r1
Dopey # df -k /vol01
Filesystem kbytes used avail capacity Mounted on
/dev/vx/dsk/DopeyDg/vol01
1048576 17751 966405 2% /vol01
Remote:
Bashful # vxdisk -eg DopeyDg list
DEVICE TYPE DISK GROUP STATUS OS_NATIVE_NAME ATTR
emc1_0072 auto:cdsdisk r1-008C DopeyDg online c1t5006048C536979A0d65s2 srdf-r2
emc1_0073 auto:cdsdisk r1-008D DopeyDg online c1t5006048C536979A0d66s2 srdf-r2
emc1_0074 auto:cdsdisk r1-008E DopeyDg online c1t5006048C536979A0d67s2 srdf-r2
emc1_0075 auto:cdsdisk r1-008f DopeyDg online c1t5006048C536979A0d68s2 srdf-r2
Bashful # df -k /vol01
Filesystem kbytes used avail capacity Mounted on
/dev/vx/dsk/DopeyDg/vol01
1048576 17750 966407 2% /vol01
c.] Unmount the remote mount point on the remote host.
Bashful # umount /vol01
d.] Deport the Diskgroup on the remote host.
Bashful # vxdg deport DopeyDg
Bashful # vxdisk -eo alldgs list | grep r2
emc1_0072 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d65s2 srdf-r2
emc1_0073 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d66s2 srdf-r2
emc1_0074 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d67s2 srdf-r2
emc1_0075 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d68s2 srdf-r2
e.] Resync the R2 devices using the data from the source R1 luns.
Dopey # symrdf -g DopeyDg establish
Execute an RDF 'Incremental Establish' operation for device group 'DopeyDg' (y/[n]) ? y
An RDF 'Incremental Establish' operation execution is in progress for device group 'DopeyDg'. Please wait...
Write Disable device(s) on RA at target (R2)..............Done.
Suspend RDF link(s).......................................Done.
Mark target (R2) devices to refresh from source (R1)......Started.
Devices: 0072-0075 in (0822,011)......................... Marked.
Mark target (R2) devices to refresh from source (R1)......Done.
Merge device track tables between source and target.......Started.
Devices: 008C-008F in (0822,011)......................... Merged.
Merge device track tables between source and target.......Done.
Resume RDF link(s)........................................Started.
Resume RDF link(s)........................................Done.
The RDF 'Incremental Establish' operation successfully initiated for device group 'DopeyDg'.
Dopey # symrdf -g DopeyDg query
Device Group (DG) Name : DopeyDg
DG's Type : RDF1
DG's Symmetrix ID : 000290300822 (Microcode Version: 5773)
Remote Symmetrix ID : 000290301414 (Microcode Version: 5773)
RDF (RA) Group Number : 11 (0A)
Source (R1) View Target (R2) View MODES
-------------------------------- ------------------------ ----- ------------
ST LI ST
Standard A N A
Logical T R1 Inv R2 Inv K T R1 Inv R2 Inv RDF Pair
Device Dev E Tracks Tracks S Dev E Tracks Tracks MDA STATE
-------------------------------- -- ------------------------ ----- ------------
DEV08C 008C RW 0 440 RW 0072 WD 0 439 S.. SyncInProg
DEV08D 008D RW 0 0 RW 0073 WD 0 0 S.. Synchronized
DEV08E 008E RW 0 0 RW 0074 WD 0 0 S.. Synchronized
DEV08F 008F RW 0 435 RW 0075 WD 0 435 S.. SyncInProg
Total -------- -------- -------- --------
Track(s) 0 875 0 874
MB(s) 0.0 54.7 0.0 54.6
Legend for MODES:
M(ode of Operation): A = Async, S = Sync, E = Semi-sync, C = Adaptive Copy
D(omino) : X = Enabled, . = Disabled
A(daptive Copy) : D = Disk Mode, W = WP Mode, . = ACp off
After a period of time, the LUNs will be synchronized.
Dopey # symrdf -g DopeyDg query
Device Group (DG) Name : DopeyDg
DG's Type : RDF1
DG's Symmetrix ID : 000290300822 (Microcode Version: 5773)
Remote Symmetrix ID : 000290301414 (Microcode Version: 5773)
RDF (RA) Group Number : 11 (0A)
Source (R1) View Target (R2) View MODES
-------------------------------- ------------------------ ----- ------------
ST LI ST
Standard A N A
Logical T R1 Inv R2 Inv K T R1 Inv R2 Inv RDF Pair
Device Dev E Tracks Tracks S Dev E Tracks Tracks MDA STATE
-------------------------------- -- ------------------------ ----- ------------
DEV08C 008C RW 0 0 RW 0072 WD 0 0 S.. Synchronized
DEV08D 008D RW 0 0 RW 0073 WD 0 0 S.. Synchronized
DEV08E 008E RW 0 0 RW 0074 WD 0 0 S.. Synchronized
DEV08F 008F RW 0 0 RW 0075 WD 0 0 S.. Synchronized
Total -------- -------- -------- --------
Track(s) 0 0 0 0
MB(s) 0.0 0.0 0.0 0.0
Legend for MODES:
M(ode of Operation): A = Async, S = Sync, E = Semi-sync, C = Adaptive Copy
D(omino) : X = Enabled, . = Disabled
A(daptive Copy) : D = Disk Mode, W = WP Mode, . = ACp off
f.] The remote (R2) LUNs will be write-disabled once again.
Bashful # vxdisk scandisks
Bashful # vxdisk -eo alldgs list | grep r2
emc1_0072 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d65s2 srdf-r2
emc1_0073 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d66s2 srdf-r2
emc1_0074 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d67s2 srdf-r2
emc1_0075 auto:cdsdisk - (DopeyDg) online c1t5006048C536979A0d68s2 srdf-r2
Bashful # vxdg -Cf import DopeyDg
VxVM vxdg ERROR V-5-1-10978 Disk group DopeyDg: import failed:
No valid disk found containing disk group
Process complete.
Issue/Introduction
