0 Considerations on T2S Migration: Special contingency cases during migration T2S Programme Office European Central Bank T2S Advisory Group - 19 November.

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Considerations on T2S Migration:Special contingency cases during migration

T2S Programme OfficeEuropean Central Bank

T2S Advisory Group - 19 November 2013 ECB-PUBLIC

Item 6.309.04.01/2013/01841

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Special contingency cases during migrationBackground

During the last months, the MSG worked on identification of major contingency scenarios applicable to the migration weekend

While for certain scenarios the way forward is clearly identified, some other issues were more difficult to apprehend: Case 1: One CSD can not migrate as originally planned

Possible options to address this issue: Move affected CSD to the contingency migration wave Postpone complete migration wave

Case 2: Entire migration wave cannot migrate as originally planned Possible options to address this issue:

Move the entire wave to the contingency wave Postpone to a later migration date

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Special contingency cases during migrationIssue – One CSD can not migrate as originally planned

Case 1:How should we manage the issue of one CSD not being able to migrate as originally planned and leaving the migration wave?

Current plan to address this issue: Exclude affected CSD and postpone its migration to

the contingency wave Remaining CSDs/CBs are to continue their migration

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Special contingency cases during migrationPoints for consideration - One CSD can not migrate

Current plan aims at minimising the impact on remaining CSDs/CBs and their communities: They have spent a lot of effort in adapting & testing, made

important investment and are ready to migrate as scheduled Their business case could be dependent on timely

implementation of migration But have all implications been measured? Current plan implies an untested migration wave composition and a

new adaptation model to be defined and implemented: Contingency configuration can not be prepared and tested in

advance due to significant number of wave composition variations

Additional activities are needed in order to address this contingency scenario: Revision of cross-CSD link configuration in T2S Resurrection of legacy links and back office systems

Changing composition of migration wave and continuing migration for remaining CSDs/CBs

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Special contingency cases during migrationPoints for consideration - One CSD can not migrate

Changing composition of migration wave and continuing migration for remaining CSDs/CBs

Existing systems/procedures before migration weekend

T2S

CSD A1

Before migration weekend

DCP

T2S

CSD A1

DCP CSD B1

CSD B2

B1 B2

B1 B2

Planned migration weekend

T2S

CSD A1

DCP CSD B1

CSD B2

A1 B2

B1

B1

B1

Contingency

migration

weekend

Systems/procedures planned for migration weekendAdapted systems/procedures due to contingency case

T2S (A1, B2)

T2S

T2S (A1)

T2S (A1)

T2S (B1, B2)

T2S (A1, B2)T2S (A1, B1, B2)

T2S (B2)

CSD B1

A1 B2

Legend

CSD B2

A1 B1

• Revision of T2S system/procedures

• Resurrection of the legacy systems/procedures

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Special contingency cases during migrationPoints for consideration - One CSD can not migrate

Special variation: CSD without links unable to migrate and rescheduled to contingency wave

Existing systems/procedures before migration weekend

T2S

CSD A1

Before migration weekend

DCP

T2S

CSD A1

DCP CSD B1

CSD B2

B2

B1 B2

Planned migration weekend

T2S

CSD A1

DCP CSD B1

CSD B2

B1

Contingency

migration

weekend

Systems/procedures planned for migration weekendAdapted systems/procedures due to contingency case

T2S (A1, B2)

T2S

T2S (A1)

T2S (B2)

T2S (A1, B1, B2)

CSD B1

CSD B2

A1

• Revision of T2S system/procedures

• Resurrection of the legacy systems/procedures

T2S (B2)

Legend

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Special contingency cases during migrationIssue – Entire migration wave can not migrate as originally planned

Case 2:How should we manage the issue of an entire migration wave not being able to migrate as originally planned, requiring the postponement of the complete migration wave?

Option A – Reschedule entire wave to contingency wave Solution implies a change of migration order

with no impact on the timing of subsequent waves

Option B – Postpone affected wave to a later migration date Solution implies a timing impact on subsequent

waves but no change of migration order

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Special contingency cases during migrationPoints for consideration - Entire migration wave can not migrate

Option A – Rescheduling to contingency wave: Overall migration planning remains stable, i.e. communicated

migration dates of subsequent waves are still valid Configuration of remaining waves will need to be revised and

legacy systems/procedures will need to be resurrected ( similar to scenario of rescheduling the migration of single CSD to contingency wave)

Option B – Postponing affected and subsequent migration waves: Efforts in user testing and migration preparation are secured,

as re-testing is limited to issue resolution Identifying and planning of alternate migration dates is

challenging, as time needed to resolve issue causing the postponement is unknown in advance

Pros and cons of both options