Web-ui shows that half of the datanodes are in decommissioning mode. What does that mean? Is it safe to remove those nodes from the network?

491

---

What is the difference between a hadoop database and relational database?

498

---

Can we deploye job tracker other than name node?

704

---

What is difference between secondary namenode, checkpoint namenode & backupnode?

509

---

Name the most common input formats defined in hadoop?

489

---

Which one is default?

531

---

Is it possible to have hadoop job output in multiple directories?

479

---

What is tasktracker in hadoop?

477

---

What is a combiner in hadoop?

554

---

Have you ever used counters in hadoop?

465

---

What are some typical functions of job tracker in hadoop?

481

---

Can you define inputsplit in hadoop?

525

---

What daemons run on master nodes?

521

---

Can you explain rack awareness?

480

---

Can you explain record reader?

474

---