Foundation Phase: Migrating from On-Premises SAP ASE (Sybase ASE to SQL Server running on Azure VM

 Foundation Phase: Migrating from On-Premises SAP ASE (Sybase ASE to SQL Server running on Azure VM

PART 1 — FOUNDATION: UNDERSTANDING THE MIGRATION 

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1. Introduction — What You Are Trying to Do 

You are migrating:

* From: On-Premises SAP ASE (Sybase ASE)

* To: SQL Server running on Azure Virtual Machines (Azure VM)

This is NOT a simple upgrade.

This is a heterogeneous migration, meaning:

* Different database engines

* Different syntax (T-SQL is similar but not identical)

* Different architecture

* Very large databases (10 TB to 100 TB)

* Mission-critical workloads (downtime = serious business impact)

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2. What Makes This Migration Difficult?

Let’s be honest — this is complex.

 

Here’s why:

2.1 Database Differences

* ASE uses **Transact-SQL (older variant)**

* SQL Server uses **modern T-SQL**

* Some features do NOT translate directly

2.2 Size Challenge

* 10TB → manageable but heavy

* 100TB → extremely large (VLDB)

This means:

* Backup/restore takes days if not optimized

* Network transfer is a bottleneck

* Storage performance matters

2.3 Mission Critical Systems

* Need **near-zero downtime**

* Need **HADR (High Availability + Disaster Recovery)**

* Need **rollback plan**

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3. Migration Strategy (Big Picture)

You must choose the right approach.

3.1 Common Migration Methods

Option 1: Offline Migration (Simple but risky)

* Stop application

* Backup ASE

* Convert + restore to SQL Server

* Downtime: LONG

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Option 2: Online Migration (Recommended)

* Initial load (bulk transfer)

* Continuous sync (CDC / replication)

* Final cutover (short downtime)

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Option 3: Hybrid Approach (Best Practice)

* Bulk load large data

* Sync incremental changes

* Final cutover

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4. Target Architecture on Azure 

You will build:

* Azure VM (Windows Server)

* SQL Server installed

* Premium SSD / Ultra Disk

* Separate disks for:

  * Data files

  * Log files

  * TempDB

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5. Tools You Will Use 

You don’t need expensive tools to start.

5.1 Core Tools

* SQL Server Management Studio (SSMS)

* Azure Data Studio

* Azure Migrate

* Database Migration Assistant (DMA)

* Bulk Copy Program (BCP)

* SQL Server Integration Services (SSIS – optional)

* AzCopy (for large data transfer)

* PowerShell

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6. BEFORE PHASE — Step-by-Step (Critical Phase)

This is where most failures happen.

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STEP 1 — Full Environment Assessment

You must understand everything before moving anything.

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6.1 Collect ASE Server Information

Run these in ASE:

```sql

sp_helpdb

go

sp_configure

go

select @@version

go

```

Capture:

* Database sizes

* Device layout

* Log sizes

* Memory configuration

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6.2 Identify Critical Databases

Ask:

* Which DBs are 24/7?

* Which DBs can tolerate downtime?

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6.3 Application Dependencies

You must identify:

* Applications using the DB

* Connection strings

* Jobs and batch processes

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6.4 Performance Baseline

Capture:

* CPU usage

* Disk IO

* Query performance

This helps compare after migration.

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STEP 2 — Compatibility Assessment

Use:

Database Migration Assistant (DMA)

What it does:

* Checks compatibility issues

* Identifies unsupported features

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Key Issues You Will Find

* Deprecated syntax

* Stored procedures not compatible

* Data types differences

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Example Issues

ASE:

```sql

select getdate()

```

SQL Server:

✔ same — OK

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But:

```sql

select @@rowcount

```

Behavior may differ.

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STEP 3 — Schema Conversion

You must convert:

* Tables

* Indexes

* Views

* Stored procedures

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Option 1: Manual Conversion

Extract schema:

```sql

sp_helptext procedure_name

```

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Option 2: Use Tools

* SSMA (SQL Server Migration Assistant for Sybase)

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STEP 4 — Data Type Mapping

Important differences:

* ASE `datetime` → SQL Server `datetime2`

* ASE `text` → SQL Server `varchar(max)`

* ASE `image` → SQL Server `varbinary(max)`

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STEP 5 — Target Azure VM Setup

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5.1 Create Azure VM

* Windows Server 2022

* SQL Server 2022

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5.2 Storage Design (VERY IMPORTANT)

For large DBs:

* Data disk (multiple)

* Log disk (separate)

* TempDB disk (separate)

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5.3 Disk Layout Example

* D:\Data

* E:\Logs

* F:\TempDB

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STEP 6 — Install SQL Server

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Best Practices

* Use default instance OR named instance

* Enable:

  * Mixed authentication

  * Max memory setting

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Set Max Memory

```sql

EXEC sp_configure 'max server memory (MB)', 50000

RECONFIGURE

```

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STEP 7 — Configure SQL Server for Large Databases

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#Enable Instant File Initialization

* Improves performance

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Set TempDB

```sql

ALTER DATABASE tempdb 

ADD FILE (NAME = tempdev2, FILENAME = 'F:\tempdb2.ndf', SIZE = 10GB)

```

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STEP 8 — Networking Setup

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* Open ports (1433)

* Configure firewall

* Test connectivity

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STEP 9 — Backup Strategy (Before Migration)

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ASE Backup

```sql

dump database dbname to "/backup/dbname.bak"

go

```

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Store backups safely

* Local

* Cloud (Azure Blob)

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STEP 10 — Migration Plan (Written Plan)

You MUST document:

* Timeline

* Downtime window

* Rollback plan

* Responsible people

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STEP 11 — Dry Run (TEST MIGRATION)

This is mandatory.

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Steps:

1. Copy small DB

2. Convert schema

3. Load data

4. Test queries

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STEP 12 — Risk Management

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Common Risks

* Data loss

* Performance degradation

* Application failure

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Mitigation

* Full backups

* Test environment

* Monitoring

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# BEFORE PHASE CHECKLIST

Follow this exactly:

* Inventory all ASE databases

* Identify critical workloads

* Run DMA assessment

* Convert schema

* Map data types

* Build Azure VM

* Configure SQL Server

* Design storage

* Test connectivity

* Take full backups

* Create migration plan

* Perform dry run