Symmetrix TimeFinder - Possible Questions for Interview
What is Business Continuity?
Business Continuity is the preparation for, response to, and recovery from an application outage that adversely affects business operations.
What are the Business Continuity tools available for symmetrix?
Power path at host end TimeFinder/Mirror, Clone and Snapshot for local replication SRDF for remote replication.
Business Continuity addresses what?
Business Continuity Solutions addresses systems unavailability, degraded application performance, or unacceptable recovery strategies.
What is RPO and RTO?
RPO refers to the maximum amount of data loss an application can tolerate as measured in time. In other words, the amount of data loss that can be tolerated (cost of transaction versus risk).
What are the different types of Device Groups?
Regular, RDF1, RDF2 and Composite group
Briefly explain baout Regular, RDF1 and RDF2 device groups?
Regular device groups are normally used for TimeFinder operations
What is composit group?
A composite group is a user-defined group of device members that can span multiple Symmetrix arrays and SRDF groups. The CG type may be defined as REGULAR,RDF1, RDF2, or RDF21, and may contain various device lists for standard, BCV, virtual (VDEV), RBCV, BRBCV, second hop standard, and second hop BCV.
What is the difference between TimeFinder and SRDF?
Time Finder is for local replication operations
What is the purpose of TimeFinder/ Mirror, Clone and SNAP?
TimeFinder/Mirror : Backups and Web content refresh
What are all possible commands used for TimeFinder Operations (Mirror, Clone and Snapshot)?
Symmir is for timefinder mirror operations
What is the BCV device?
BCV is Business Continuance Volume
Explain step by step procedure for TimeFinder Mirror Operations?
Establish: Synchronize the standard volume to the BCV volume
What is the status of Source and Target devices at the time of Establish, Split and Restore in mirror operations?
Establish: STD device have R/W access and BCV device is in NR state.
How will synchronization happen when perform establish?
The Symmetrix array checks that both the standard device and the BCV device are the same size, the device specified as the BCV has the BCV attribute, the standard device does not already have a BCV device assigned to it.
What is the background process in split operation?
Command validity is checked. For example, the Symmetrix array makes sure that the standard device has an active BCV mirror and that the standard and BCV devices comprise a BCV pair.
What is default option while performing establish?
Incremental is the default action for establish.
What is Power path Split?
Power Path holds I/O during split - Read and write I/O, executed from host doing I/O, affects only one host, does not require independent access to a gatekeeper.
What is ECA (Enginuity Consistent Assist) split?
Symmetrix holds I/O during split - Write I/O (subsequent reads after first write), Executed by any Symmetrix-attached host, multiple host support, requires independent access to a gatekeeper.
What are the precautions we have to take while performing establish?
Host access to BCV devices must be stopped.
What are the precautions we have to take while restoring a mirror?
All access to the STD device must be stopped. Applications must be stopped, file systems must be unmounted, and volume groups must be deactivated when a restore is initiated. Since the host is having read and write access to the standard device, if any application is using the standard volume during a restore, the results would be unpredictable.
What is Protected BCV Establish?
Both M1 and M2 of standard device instantly synchronized with the M1 and M2 of 2-way mirror BCV.
What is reverse split?
Data will be moved from the M2 mirror of the BCV to its M1 mirror.
What is Protected BCV Restore?
A protected restore feature allows the contents of a BCV to remain unchanged during and after a restore operation, even while the BCV and the standard are joined.
How many BCVs can be supported in multi BCV functionality?
How many BCVs can be established concurrently to the standard volume?
Is TimeFinder Mirror Supports concurrent restores?
Concurrent restores are not allowed.
Is the BCV can be mounted to the source host?
BCV mirror can be mounted to same host but there will duplicate disk signatures/volume IDs need to change.
One device can be a member of how many device groups?
Only one device group
Device Groups are host based or Array based?
Host based. If we enable the GNS in symmetrix array then we can create array wide device group.
What is foreground and background instant split?
Foreground split completes instantly and returns a success status to the production.
Expbrlain Step by step procedure for TimeFinder Clone Operations?
Create: Create relationship between standard and Clone
What are the different options with clone create and Explain?
CopyOnAccess: Only modified tracks are copied to clone volume after activation
Can we use STDs as a target for Clone?
Yes, we can use standard or BCV as a clone.
How many CopyOnAccess sessionw symclone will support?
Up to 16 CopyOnAccess sessions
How many concurrent Full copied session clone will support?
Up to 4 concurrent Full Copied sessions
When we have to use –defferential option while create a clone session?
If clone recreate is planned or incremental restore is planned.
What will happen when we activate the clone session?
Places the target in the Read/Write (RW) state
Explain Step by step procedure for TimeFinder Snap Operations?
How the copy session works in symsnap operation?
Once the Time Finder Snap session is activated:
What is the background process while terminating the clone session?
When a copy session is terminated
How many snapshots can be created from a single source volume?
Upto 15 snap sessions can be create with source volume.
How many snapshot can be created in multi virtual?
What will happen if save area is run out of space?
The target VDEV goes in Not Ready (NR) state, applications beware! Copy-on-write is disabled and the source track is changed.
What is the recommended size of VDEV?
1/600th the size of a source device
How the data will be stored in save devices in a save pool?
Data will be stored in a save pool as a round-robin manner.
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