When SAP System Copy Fails at ‘Start Instance’: A Memory Diagnosis from the Trenches

Hiroshi Ozaki breaks down what you need to know

A system copy that aborts right at the “Start Instance” step can ruin a project timeline. You’ve exported the database, restored it on the target host, and run the post‑copy steps—only to see the work processes crash immediately with a memory allocation error. The first reaction is often frustration, followed by a hurried server reboot. Over three decades of working with SAP landscapes, I’ve seen this scenario too many times. The reboot may get you past the hump, but it rarely addresses the root cause, and it’s certainly not the mindset of a strategic Basis professional.

The Real Story

The error typically surfaces in the instance’s developer trace as something like:

EsInit(Environ) ... Cannot allocate memory for ...

The start process (sapstart) or dispatcher cannot reserve the shared memory segments configured in the instance profile. This happens because the target host’s physical memory, swap space, or kernel parameters don’t match what the imported profile demands. After a system copy, the target instance inherits the source system’s profile parameters—often tuned for a large production box—without adjusting them for the sandbox or development environment. Parameters like PHYS_MEMSIZE, em/initial_size_MB, and zcsa/table_buffer_area may request far more memory than the target server can provide.

Interestingly, the error does not always indicate an outright shortage of physical RAM. Over time, the operating system’s memory can become fragmented by repeated starts and stops, background jobs, or leftover shared memory segments from previous failed attempts. That’s why a simple server restart often resolves the issue: the reboot clears the fragmentation, reclaiming contiguous memory blocks large enough to satisfy the instance’s demands. In my Fujitsu days, we called this the “morning coffee reboot”—a quick fix that temporarily masks the real design gap.

What This Means for You

For the BASIS consultant, this error is a warning sign of incomplete pre‑copy planning. If you’re rushing a system refresh to meet a testing deadline, you might be tempted to reboot and move on. But if the underlying memory sizing is wrong, the instance will behave erratically later—sluggish performance, unexpected work process terminations, or even an inability to start after the next maintenance window. I recall a 2013 project where a customer’s QAS system collapsed mid‑business because the post‑copy memory tweaks were never applied; the reboot had only bought them two weeks.

For infrastructure teams and sysadmins, the incident highlights a cultural gap. In many organizations, the Basis team assumes the hardware is ready, and the infrastructure team assumes SAP will “just work.” This siloed approach is the enemy of sustainable digital transformation. A mature practice requires that before every system copy, both sides jointly review:

• Target host physical memory and swap (minimum: source system’s used memory + 20% overhead)
• OS shared memory limits (kernel.shmmax, kernel.shmall on Linux)
• SAP profile parameters that control memory allocation, with a view to scaling them down for non‑production environments

Without this collaboration, even a successful restart today merely postpones the problem.

Action Items

• Before the system copy: Capture the source instance’s memory‑relevant profile parameters. Compare them with the target host’s available memory. Adjust parameters like PHYS_MEMSIZE, em/initial_size_MB, and em/global_area_MB in the target’s default profile (DEFAULT.PFL) before starting the instance for the first time. A safe starting point is 50–70% of the physical RAM for PHYS_MEMSIZE on a dedicated SAP host.
• If the error occurs: Don’t immediately reboot. First, examine the work process trace (work/dev_w0, dev_disp) for explicit allocation failures. Check OS memory with free -m and ipcs -m (to see if leftover shared memory segments are consuming resources). If fragmentation is the culprit, a server restart may be the quickest path, but only if total free memory meets SAP’s demand.
• Engage the sysadmin with a clear request: “We need to restart the host after ensuring that no other critical services are affected. Post‑reboot, please verify memory availability and confirm the kernel shared memory parameters are set to support an SAP instance of X GB.” The restart requires sysadmin privileges and proper change approval—this is an opportunity to model collaborative behavior, not a back‑door workaround.
• After the instance starts: Immediately adjust the profile parameters to match the target environment, then perform a controlled restart of the SAP system. This locks in the sustainable configuration. Update your system copy runbook to include a mandatory “Target Sizing Check” section.

Community Perspective

A recent discussion on Spiceworks[iii] captures the classic practitioner reflex: the user reported the memory error during “Phase Start Instance,” and the response was to restart the server. Several community members confirmed this worked for them. This isn’t wrong—it’s pragmatic—but it reveals how easily we accept temporary fixes as permanent solutions. A seasoned consultant listens to that collective experience, extracts the tactical relief, and then asks, “What process change will prevent this from happening the next time?” The Spiceworks thread, while short, underscores that many Basis professionals still lack a structured approach to system copy preparation.

Bottom Line

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References

• Error in SAP System Copy in Phase Start Instance
• SAP AI Core Documentation
• SAP Community Hub

References

• SAP AI Core Documentation
• SAP Community Hub
• Error in SAP System Copy in Phase Start Instance