NetWare Data Protection Mechanisms | Generated by AI
Question: In Novell NetWare, to prevent data from being written to unreliable disk blocks, two complementary technologies are used for data protection. What are they?
Answer:
The correct answer is B. Hot fix and read-after-write verification.
Detailed explanation:
Novell NetWare (especially versions such as NetWare 3.x and 4.x) used two main complementary techniques to protect against writing data to bad or unreliable disk sectors:
- Hot Fix (热调整 / Hot Fix Redirection Area)
- Novell maintains a small reserved area on the disk called the Hot Fix redirection area.
- When a write error occurs or during surface scans, bad blocks are detected.
- Instead of failing the write, NetWare redirects the data to a good block in the Hot Fix area and updates the Hot Fix table.
- This happens transparently — the operating system continues to see the original logical block address.
- Purpose: prevents future writes to known bad blocks and corrects errors on-the-fly.
- Read-After-Write Verification (写后读验证)
- After every write operation, the file server immediately reads back the data just written.
- If the read-back data does not match what was sent, the write is considered failed.
- The server then marks the block as bad (redirects it via Hot Fix) and retries the write to another location.
- Purpose: detects write errors immediately, ensuring data is not silently corrupted on unreliable media.
These two techniques work together:
- Read-after-write actively detects write problems in real time.
- Hot Fix provides the mechanism to recover from and permanently avoid bad blocks.
Why the other options are incorrect:
- A. Hot fix and disk mirroring → Disk mirroring is for redundancy (two copies of data), not specifically for preventing writes to bad blocks.
- C. Disk mirroring and read-after-write verification → Mirroring protects against complete disk failure, not individual bad sectors on a single drive.
- D. Disk mirroring and disk duplexing → Both are forms of RAID-1 style mirroring (duplexing uses separate controllers), focused on fault tolerance, not bad-block handling.
Memory tip (as provided):
“热写防错双保险” → Hot fix + write-then-read verification are the two complementary protections against bad-block writes.
References:
- None (standard Novell NetWare storage protection mechanisms, widely documented in legacy NetWare administration guides)