EMC Storage Product Knowledge Sharing

TimeFinder/Mirror Consistent Split

2010-01-31T09:18:00.000-08:00

Think when you are creating a point-in-time image for multiple devices. It is easy to create a point-in-time image of entire set of logical device at same time. In order achieve this you need to shut down an application so that no IO will occurs while you creating a point-in-time image. This is big problem in today’s environment where every company looking solution for zero down time.
The EMC provided solution to this problem is called “Enginuity Consistency Assist”. When you create a set of sessions and invoke Enginuity Consistency Assist, the Symmetrix aligns the I/O of those devices and halts all I/O from the host systems very briefly—much faster than the applications can detect—while it creates the session. It then resumes normal operation without any application impact.
TimeFinder Consistent Split using (TimeFinder/Consistency Groups) allows the splitting off of a consistent, re-startable image of an Oracle database instance within seconds with no interruption to the online Oracle database instance.
- Allows users to split off a dependent write consistent, re-startable image of application without interrupting online services
- Using TimeFinder/Consistency Groups to defer write I/O at the Symmetrix before a split
- Consistent split can be performed by any host running Solutions Enabler connected to the Symmetrix
- Tested and available including HP-UX, Solaris, AIX, Linux, and Windows
- No database shutdown or requirement to have database put into backup mode (Oracle).

Using TF/CG, consistent splits helps to avoid inconsistencies and restart problems that can occur with using Oracle hot-backup mode (not quiescing the database).

The major benefits of TF/CG are:
• No disruption to the online Oracle database to obtain a Point-in-Time image
• Provides a consistent, re-startable image of the Oracle database for testing new versions or database patch updates before deploying for use in production environments
• Can be used to obtain a business point of consistency for business restart requirements for which Oracle has been identified as one of multiple databases for such an environment.

The same benefits apply using TF/CG in a clustered environment as in a non-clustered environment:
- No disruption to the online Oracle database to obtain a Point-in-Time image in a Oracle single instance environment or when using Oracle Real Application Clusters
- Provides a consistent, re-startable image of the Oracle database for testing new versions or database patch updates before deploying for use in clustered production environments
- Can be used to obtain a business point of consistency for business restart requirements for which Oracle has been identified as one of multiple databases for such an environment.

Understanding Auto Provisioning in VMAX

2009-12-29T12:12:00.000-08:00

Auto-provisioning requires Enginuity 5874 or later. It simplify Symmetrix provisioning by allowing you to create group of devices like storage group in CLARiiON, Front-End Port Group and Host Initiators Group and then associate these groups with each other in a masking view.

The following are the basic steps for provisioning Symmetrix using Auto-Provisioning:-

1) Create a Storage Group
2) Create a Port Group
3) Create an Initiator Group
4) Associate the groups in a Masking View.

Creating Storage Group:- It is component of Auto-Provisioning group and FAST ( Will discuss about FAST in later post), both require Enginiuity 5874. The maximum number of storage group allowed per array is 8192. A storage group can contain up to 4096 devices. A Symmetrix device can belong to more than one storage group.

Note:- By default Dynamic LUN addresses will assigned to each device. If can manually assign the host LUN addresses for the device you are adding to the group by clicking Set LUN Address- Storage group dialog box.

Creating Port Group:- A port can belong to more than one port group and port must have the ACLX bit enabled. For example if you want FA 5A and 12 A for windows operating system, you can create port group name called WIN_PortGrp or Win_FA5A_FA12A_PrtGrp etc.

Creating Initiator Group:- The maximum number of initiator groups allowed per Symmetrix array is 8000. An initiator group can contain up to 32 initiator of any type and contain other initiator groups (cascaded to only one level).

Initiator Group name must be unique from other initiator groups on the array and cannot exceed 64 characters. Initiator group names are case-insensitive.

Creating Masking view:- It just a co-relation between Storage Group, Port Group and Initiator Group and you are done! Device will be mapped automatically to selected port group and masked to selected initiator groups.

SRDF Pair Status

2009-09-16T12:56:00.000-07:00

SRDF/S and SRDF/A configuration involves tasks such as suspending and resuming the replication, failover from R1 side to R2, restoring R1 or R2 volumes from their BCV, and more. You perform these and other SRDF/S or SRDF/A operations using both symrdf and TimeFinder command symmir. The below details are for SRDF Pair states during SRDF procedure.

SyncInProg :- A synchronization is currently in progress between the R1 and the R2. There are existing invalid tracks between the two pairs and the logical link between both sides of an RDF pair is up.

Synchronized :- The R1 and the R2 are currently in a synchronized state. The same content exists on the R2 as the R1. There are no invalid tracks between the two pairs.

Split :- The R1 and the R2 are currently Ready to their hosts, but the link is Not Ready or Write Disabled.

Failed Over :- The R1 is currently Not Ready or Write Disabled and operations been failed over to the R2.

R1 Updated :- The R1 is currently Not Ready or Write Disabled to the host, there are no local invalid tracks on the R1 side, and the link is Ready or Write Disabled.

R1 UpdInProg :- The R1 is currently Not Ready or Write Disabled to the host, there are invalid local (R1) tracks on the source side, and the link is Ready or Write Disabled.
Suspended :- The RDF links have been suspended and are Not Ready or Write Disabled. If the R1 is Ready while the links are suspended, any I/O accumulates as invalid tracks owed to the R2.

Partitioned :- The SYMAPI is currently unable to communicate through the corresponding RDF path to the remote Symmetrix. Partitioned may apply to devices within an RA group. For example, if SYMAPI is unable to communicate to a remote Symmetrix via an RA group, devices in that RA group are marked as being in the Partitioned state.

Mixed :- Mixed is a composite SYMAPI device group RDF pair state. Different SRDF pair states exist within a device group.

Invalid :- This is the default state when no other SRDF state applies. The combination of R1, R2, and RDF link states and statuses do not match any other pair state. This state may occur if there is a problem at the disk director level.

Consistent :- The R2 SRDF/A capable devices are in a consistent state. Consistent state signifies the normal state of operation for device pairs operating in asynchronous mode.