VMAX Replication Interview Questions

VMAX Replication Interview Questions

Question
For a single device(LUN) how many clones and snaps we can take ?
Answer
Clone= 8 differential , 16 (14+2 recovery) Non-diff Snap= 16 and 128 in case of Virtual snap enabled
 
Question
Why is “-invalidate” used while enabling SRDF ? what is its utility ?
 
Answer
It allows the creation of SRDF pairs but not bring up the link….it also helps us to decide which data you want to dicard while creation R1/R2. Helpful with RDF swap.
 
Question
List out the features of VMAX replication ?
 
Answer
VMAX provided the world class enterprise storage replication features. Which are categorized in 02. Local Protection and Remote protection. Local and remote protection components has already explained in first Question.
 
Question
What is the diff. between DMAX and VMAX ?
Answer
There are many differences in term of remote replication. VMAX has intrduced some new features which were not in DMX. Federated Live Migration, TimeFinder/ Snap VP, SRDF/A Multi Session Consistency, SRDF/A Consistency Exempt Feature, Recoverpoint Splitter, SRDFe, FAST VP , coordination with SRDF, SRDF/EDP RDF/Extended Distance Protection (SRDF/EDP) , cascaded SRDF, SRDF/Star a concurrent R2 (R22), Cascaded TimeFinder/Clone, SNAP Recreate, Duplicate TF/SNAP, Control SNAP volume in Cold Push Open Replicator for Symmetrix etc.
 
Question
What is the difference between remote replication SRDF/S,SRDF/A SRDF/AR and SRDF/EDP Explain the funtionality of each.
Answer
These are different features of remote replication in VMAX: SRDF/S: for near DR sites, which is synchronous, bandwidth consuming, but real time replication SRDF/A: for near as well as far site, which is a-synchronous, bandwidth effecient, but delayed replication SRDF/AR: it is a mixed replication type, includes SRDF/S to bunker site and SRDF/A ACP mode for remote site. SRDF/EDP: it is a cascaded mode of SRDF/S.
 
Question
Why is -invalidate used while enabling SRDF ? What is its utility ?
 
Answer
 
It has already answered before. Establish is the command option which replaced in new enginuity releases.
 
Question
Is replication possible between Symmetrix DMX-1000 and V-max data via SRDF?
 
Answer
Not possible. due to different enginuity base code.
 
Question
How can I can add newly paired devices into existing RDF group ? I normally do it by movepair command. Is there any other way ?
Answer
SRDF/A Consistency Exempt Feature can help in this, adding without suspend.
 
Question
How effectivly deduplicaiton over replication works ?
Answer
There is no data deduplication support on VMAX.
 
Question
Can you explain more on srdf/cg ?
 
Answer
It is used for multi consistency sessions, where you want to include multiple symmetrix storages RDF sessions to run together. and suspend one if other has any problem with data propagation.
 
Question
Can you please elaborate on moving newly paired devices to existing RDF group with commands ?
Answer
It seems like you need solution on it. pls. mail me your exact query with some details about your setup. i will share solution on mail.
 
Question
What is the purpose of Adaptive copy mode ?
Answer
It is SRDF/A feature for data migration and DC movement.
 
Question
What is Clustered SRDF/AR
Answer
Clustered SRDF/AR provides the feature to start, stop, and restart replication sessions from clustered host connected to any local Symmetrix array participating in the replication session. The clustered SRDF/AR environment allows the replication log file to be written directly to the Symmetrix File System (SFS) instead of the local host. If the primary node should fail, then any locally attached host to the Symmetrix array containing the log file would then be able to restart the SRDF/AR session from where it left off.
 
Question
What is SRDF Domino mode ?
Answer
Domino Mode is used in conjunction with other SRDF modes except SRDF/A. It effectively stop all write operations to both source and target volumes if target volume become unavailable, or if all SRDF links become unavailable.
 
Question
What is semi-synchronous SRDF ?
Answer
it is feature which is in between the Sync and Async mode of SRDF, where data pkt-1 writes to local cache and sent to remote symmetrix storage before 2nd data cycle arrives. it is better than SRDF/S
 
Question
 
What is Writing Pending and Disk Mode of Adaptive Copy?
Answer
I/O is accumulates in Symmetrix cache in Write Pending Mode I/O is accumulates in R1 volume in Disk Mode
 
Question
How many R2 devices can be paired with one R1 device concurrently?
Answer
02 (SRDF/cascaded, STAR, EDP, AR)
 
Question
What are the new features of vmax replication?
 
Answer
Federated Live Migration TimeFinder/ Snap VP SRDF/A Multi Session Consistency SRDF/A Consistency Exempt Feature Recoverpoint Splitter SRDFe FAST VP coordination with SRDF SRDF/EDP RDF/Extended Distance Protection (SRDF/EDP) cascaded SRDF SRDF/Star a concurrent R2 (R22) Cascaded TimeFinder/Clone SNAP Recreate Duplicate TF/SNAP Control SNAP volume in Cold Push Open Replicator for Symmetrix
 
Question
 
What are the limitations of vmax 10k replication?
Answer
VMAX 10k Limitations: Local Replication: does not support Timefinder/SNAP, we cannot create savepool from the solution enabler, only deafault pools can be used for DSE purpose. Remote replication: we cannot create dynamic RDF capable devices from the solution enabler and many more
 
Question
 
What is TimeFinder VP Snap?
Answer
TimeFinder VP/Snap is a space saving local replication feature introduced with Enginuity 5876. Multiple clone targets of a source device can share track allocations within the same Thin Pool. Up to 32 sessions can be created for the same source device
 
Question
What is the difference between TimeFinder Snap and TimeFinder VP Snap?
Answer
1. tf snap works with symsnap command and tf vp works with symclone -vse option 2) in snap, protected tracks from source are copied to snap pool but in virtual snap, the protected tracks are copied to pools. You source and target both could reside in the same thin pool or in different. 3) VP Snap leverages TimeFinder/Clone technology to create space-efficient snaps for thin devices by allowing multiple sessions to share capacity allocations within a thin pool. 4) In diag below, i have got one thin source bound to a pool and three clone (vp snap) devices bound to another pool but the data of three targets are being shared. I can also have source and target bound to the same thin pool to save space.
 
Question
What is dynamic R1/R2 swap?
 
Answer
 
The dynamic R1/R2 swap feature swaps the SRDF personality of the SRDF device designations of a specified device or composite group.