Sandisk Software Engineer Interview Guide

The 60-second brief

A Software Engineer at Sandisk works at the critical intersection of software development, embedded firmware, and specialized hardware storage architecture. Unlike standard high-level application development roles, engineering at Sandisk requires a deep understanding of how code interacts directly with silicon, non-volatile memory controller logic, and low-level storage protocols. Software engineers build the essential logic that drives solid-state drives (SSDs), embedded flash storage, and next-generation memory systems used by millions of global consumers and massive enterprise data centers. The impact of this role is immense: performance optimizations in firmware or low-level software stack code directly determine read/write speeds, endurance, and power consumption of hardware components.

This guide is scoped to a Software Engineer candidate at Sandisk.

Focus areas

• NAND Flash / Flash Memory Basics
• C
• Dynamic Memory Allocation (malloc, malloc-based 2D arrays)

The Sandisk interview process

Sandisk candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Initial Screening

Focus on background review and basic engineering logic, often including a proctored technical screening exam.

What to demonstrate

• Focus on background review and basic engineering logic, often including a proctored technical screening exam
• Depth in NAND Flash / Flash Memory Basics

How to prepare

• Be able to walk your CV end to end in two minutes, and say why this company specifically.
• Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Phone Screen

Candidates who succeed in the initial screening advance to technical phone screens or onsite interview loops.

What to demonstrate

• Candidates who succeed in the initial screening advance to technical phone screens or onsite interview loops
• Depth in NAND Flash / Flash Memory Basics

How to prepare

• Be able to walk your CV end to end in two minutes, and say why this company specifically.
• Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Onsite Interview

An intensive series of technical and managerial interviews, typically including four to six back-to-back technical modules.

What to demonstrate

• An intensive series of technical and managerial interviews, typically including four to six back-to-back technical modules
• Depth in NAND Flash / Flash Memory Basics

How to prepare

• Answer aloud and timed: Explain how function overriding can be simulated or handled in C when parameters vary at runtime.
• Answer aloud and timed: Write code to reverse alternative $k$ nodes of a linked list or clone a linked list containing random pointers.

Final HR Interview

Ends the onsite loops with a dedicated HR and leadership interview.

What to demonstrate

• Ends the onsite loops with a dedicated HR and leadership interview
• Depth in NAND Flash / Flash Memory Basics

How to prepare

• Answer aloud and timed: Implement a algorithm to detect a loop in a linked list using pointer techniques.
• Answer aloud and timed: How do you construct a custom hash map data structure from scratch using raw C structs?

Where candidates lose points

Master Raw Pointer Mechanics

Practice writing C code on paper or whiteboards without an IDE. Focus on pointer manipulation, memory allocation checks, string processing, and custom dynamic structure operations.

Understand the Hardware Boundary

Even for pure software roles, review basic digital electronics concepts—such as flip-flops, multiplexers, sequence detectors, setup/hold times, and basic CMOS transistor behavior. Showing an understanding of hardware principles sets you apart.

Be Prepared to Solve Logic Puzzles

Interviewers at Sandisk frequently use math and analytical logic puzzles (e.g., egg drop scenarios, clock frequency multipliers) to assess your real-time problem-solving approach. Walk through your thought process clearly out loud.

Be Detailed on Resume Projects

Expect deep-dive questions on every project, tool, or protocol listed on your resume. Interviewers will test the depth of your personal contributions, asking why specific technical trade-offs were made.

Questions & practice

Write C code to allocate memory dynamically for a 2D array using pointers (int arr).

Medium · C & Embedded Systems Programming

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Implement custom string parsing such as strtok without using standard library utility functions.

Medium · C & Embedded Systems Programming

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

How do you avoid structure padding in C, and why is byte alignment critical in memory-constrained devices?

Medium · C & Embedded Systems Programming

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Explain how function overriding can be simulated or handled in C when parameters vary at runtime.

Medium · C & Embedded Systems Programming

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Write code to reverse alternative $k$ nodes of a linked list or clone a linked list containing random pointers

Medium · Data Structures & Algorithms

Write code to reverse alternative $k$ nodes of a linked list or clone a linked list containing random pointers.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Implement a algorithm to detect a loop in a linked list using pointer techniques.

Medium · Data Structures & Algorithms

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

How do you construct a custom hash map data structure from scratch using raw C structs?

Medium · Data Structures & Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Write a program to count the number of active set bits ('1's) in a binary variable efficiently.

Medium · Data Structures & Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Write an optimal binary search algorithm and adapt it for specialized structures like rotated sorted arrays.

Medium · Data Structures & Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Explain how semaphores and mutexes work, and demonstrate how to handle the classic producer-consumer problem w

Medium · Operating Systems & Systems Architecture

Explain how semaphores and mutexes work, and demonstrate how to handle the classic producer-consumer problem without starvation.

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

What is the difference between user space and kernel space memory management?

Medium · Operating Systems & Systems Architecture

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

How do virtual memory, page tables, and file system formats like FAT32 and NTFS manage physical storage hardwa

Medium · Operating Systems & Systems Architecture

How do virtual memory, page tables, and file system formats like FAT32 and NTFS manage physical storage hardware?

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Explain the underlying physical operation and differences between CMOS NAND and NOR memory structures.

Medium · Memory Architecture & Hardware Fundament

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

What are the concepts of wear leveling, garbage collection, and flash translation layers in non-volatile stora

Medium · Memory Architecture & Hardware Fundament

What are the concepts of wear leveling, garbage collection, and flash translation layers in non-volatile storage?

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

1. Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
2. Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
3. Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
4. Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

• The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
• How do you verify the backfill actually finished, given rows are still being inserted while it runs?

Write the update path that detects a concurrent edit

Medium · optimistic concurrency · transactional outbox · audit history

resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.

Approach

1. One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
2. Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
3. State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
4. Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.

Follow-up

• A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
• Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?

What are storage classes in C, and what are the specific architectural uses for static and extern variables?

Medium · C & Embedded Systems Programming

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

What is the difference between a process and a thread, and how are resources partitioned between them?

Medium · Operating Systems & Systems Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

How would you design and implement the system functionality of the UNIX tail command?

Medium · Operating Systems & Systems Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Explain setup time and hold time requirements in digital circuits and how timing violations impact execution.

Medium · Memory Architecture & Hardware Fundament

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

How do threshold voltages ($V_{th}$) and short-channel effects operate inside MOSFET structures?

Medium · Memory Architecture & Hardware Fundament

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Draw and explain basic digital logic components, sequence detectors, or FIFO buffers using raw logic gates.

Medium · Memory Architecture & Hardware Fundament

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

How do you approach debugging an unexpected system crash or analyzing a generated crash core dump file?

Medium · Behavioral & Puzzles

Approach

1. Establish what changed and when, before forming any theory.
2. Pick a bisection that eliminates candidates whichever way it turns out.
3. Check the instrumentation before believing the symptom.
4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

• What would you look at first, and what would it rule out?
• How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics Sandisk candidates report.

Day 1 — Map the Sandisk loop

• Write out the reported sequence: Initial Screening, Technical Phone Screen, Onsite Interview, Final HR Interview.
• For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 4 reported rounds, with the weakest marked.

Day 2 — Work NAND Flash / Flash Memory Basics

• Spend the session on NAND Flash / Flash Memory Basics, which Sandisk candidates report being tested on.
• Write one worked example in NAND Flash / Flash Memory Basics and time yourself on it.

Deliverable: One timed worked example in NAND Flash / Flash Memory Basics.

Day 3 — Work C

• Spend the session on C, which Sandisk candidates report being tested on.
• Write one worked example in C and time yourself on it.

Deliverable: One timed worked example in C.

Day 4 — Work Dynamic Memory Allocation (malloc, malloc-based 2D arrays)

• Spend the session on Dynamic Memory Allocation (malloc, malloc-based 2D arrays), which Sandisk candidates report being tested on.
• Write one worked example in Dynamic Memory Allocation (malloc, malloc-based 2D arrays) and time yourself on it.

Deliverable: One timed worked example in Dynamic Memory Allocation (malloc, malloc-based 2D arrays).

Day 5 — Answer out loud: C & Embedded Systems Programming

• Answer aloud, timed: Write C code to allocate memory dynamically for a 2D array using pointers (int arr).
• Answer aloud, timed: Implement custom string parsing such as strtok without using standard library utility functions.

Deliverable: Spoken answers to 2 reported C & Embedded Systems Programming question(s), under time.

Day 6 — Answer out loud: Data Structures & Algorithms

• Answer aloud, timed: Write code to reverse alternative $k$ nodes of a linked list or clone a linked list containing random pointers.
• Answer aloud, timed: Implement a algorithm to detect a loop in a linked list using pointer techniques.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms question(s), under time.

Day 7 — Answer out loud: Operating Systems & Systems Architecture

• Answer aloud, timed: What is the difference between a process and a thread, and how are resources partitioned between them?
• Answer aloud, timed: Explain how semaphores and mutexes work, and demonstrate how to handle the classic producer-consumer problem without starvation.

Deliverable: Spoken answers to 2 reported Operating Systems & Systems Architecture question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Solve the classic 2 eggs and 100 floors puzzle to determine the minimum drop attempts required.

Medium · Behavioral & Puzzles

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Describe a situation where you faced a major technical challenge or conflict in a team project and how you res

Medium · Behavioral & Puzzles

Describe a situation where you faced a major technical challenge or conflict in a team project and how you resolved it.

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Why do you want to work for Sandisk, and what key engineering strengths do you bring to our storage team?

Medium · Behavioral & Puzzles

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?