Hadoop: How to find which file is healthy

by
Hadoop provides file system health check utility which is called "fsck". Basically, it checks the health of all the files under a path It also checks the health of all the files under the '/'(root).
  • BIN/HADOOP fsck / - It checks the health of all the files
  • BIN/HADOOP fsck /test/ - It checks the health of files under the path
By default fsck utility cannot do anything for under replicated blocks and over replicated blocks. Hadoop itself heal the blocks.
Healthy file checking ides

 How to find which file is healthy

  • It prints out dot for each healthy file
  • It will print a message for each file, if it is not healthy, also for under replicated blocks, over replicated blocks, mis-replicated blocks, and corrupted blocks.
  • By default fsck utility cannot do anything for under replicated blocks and over replicated blocks. Hadoop itself heal the blocks.

How to delete corrupted blocks

  • BIN/HADOOP fsck -delete block-names
  • It will delete all corrupted blocks
  • BIN/HADOOP fsck -move block-names
  • It will move corrupted blocks to /lost directory
  • Other options we can use with fsck:
    • files
    • blocks
    • locations

Comments

Post a Comment

Thanks for your message. We will get back you.

Most Popular

7 AWS Interview Questions asked in Infosys, TCS

by
Image
I have shared 7 amazing AWS interview questions for your quick reference. 1). What is AWS? Amazon Web Services (AWS) provides on-demand computing resources and services in the cloud, with pay-as-you-go pricing. For example, you can run a server on AWS that you can log on to, configure, secure, and run just as you would a server that's sitting in front of you 2). What you can do with AWS? Store public or private data. Host a static website. These websites use client-side technologies (such as HTML, CSS, and JavaScript) to display content that doesn't change frequently. A static website doesn't require server-side technologies (such as PHP and ASP.NET). Host a dynamic website or web app. These websites include classic three-tier applications, with web, application, and database tiers. Support students or online training programs. Process business and scientific data. Handle peak loads. AWS Questions 3). What is the Security group? A security group acts as a virtual fi
Read more

How to Decode TLV Quickly

by
Image
In TLV, the format is Tag, Length, and Value. The TLV protocol needs this type of data. Here you will know how to decode TLV data.  According to IBM , TLV data is three parts. The tag tells what type of data it is. The length field denotes the length of the value. The Value-field denotes the actual value. Structure of TLV. TLV comprises three field values.  Tag Length Value How to Decode TLV EMV formulated different tags. They have their meanings. Usually, the Tag and Length together takes 1 to 4 bytes. 1. The Best example for TLV. In the below example, you can find the sample TAG, LENGTH, and VALUE fields. [Tag][Value Length][Value] (ex. " 9F4005F000F0A001 ") where,  Tag Name =  9F40 Value Length (in bytes) =  05  Value (Hex representation of bytes. Example, "F0" – 1-byte) =  F000F0A001 In the above message, tag 9F40 has some meaning designed by EMV company. Here  you can find a list of EMV Tags. 2. How to read the TLV Tag: 1 or 2 bytes. Length: Length of the Value
Read more

Hyperledger Fabric: 20 Real Interview Questions

by
Image
I am practicing Hyperledger. This is one of the top listed blockchains. This architecture follows R3 Corda specifications. Sharing the interview questions with you that I have prepared for my interview. Though Ethereum leads in the real-time applications. The latest Hyperledger version is now ready for production applications. It has now become stable for production applications. The Hyperledger now backed by IBM. But, it is still an open source. These interview questions help you to read quickly. The below set of interview questions help you like a tutorial on Hyperledger fabric. Hyperledger Fabric Interview Questions 1). What are Nodes? In Hyperledger the communication entities are called Nodes. 2). What are the three different types of Nodes? - Client Node - Peer Node - Order Node The Client node initiates transactions. The peer node commits the transaction. The order node guarantees the delivery. 3). What is Channel? A channel in Hyperledger is the subnet of
Read more