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Red Hat Enterprise Linux Troubleshooting Guide

You're reading from   Red Hat Enterprise Linux Troubleshooting Guide Identify, capture and resolve common issues faced by Red Hat Enterprise Linux administrators using best practices and advanced troubleshooting techniques

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Product type Paperback
Published in Oct 2015
Publisher
ISBN-13 9781785283550
Length 458 pages
Edition 1st Edition
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Author (1):
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Benjamin Cane Benjamin Cane
Author Profile Icon Benjamin Cane
Benjamin Cane
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Table of Contents (14) Chapters Close

Preface 1. Troubleshooting Best Practices 2. Troubleshooting Commands and Sources of Useful Information FREE CHAPTER 3. Troubleshooting a Web Application 4. Troubleshooting Performance Issues 5. Network Troubleshooting 6. Diagnosing and Correcting Firewall Issues 7. Filesystem Errors and Recovery 8. Hardware Troubleshooting 9. Using System Tools to Troubleshoot Applications 10. Understanding Linux User and Kernel Limits 11. Recovering from Common Failures 12. Root Cause Analysis of an Unexpected Reboot Index

Using mdadm to examine the superblock


To view the event count, we will use the mdadm command with the --examine flag to examine the disk devices:

[nfs]# mdadm --examine /dev/sda1
/dev/sda1:
          Magic : a92b4efc
        Version : 1.0
    Feature Map : 0x1
     Array UUID : 7adf0323:b0962394:387e6cd0:b2914469
           Name : localhost:boot
  Creation Time : Wed Apr 15 09:39:22 2015
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 1023968 (500.07 MiB 524.27 MB)
     Array Size : 511936 (500.02 MiB 524.22 MB)
  Used Dev Size : 1023872 (500.02 MiB 524.22 MB)
   Super Offset : 1023984 sectors
   Unused Space : before=0 sectors, after=96 sectors
          State : clean
    Device UUID : 92d97c32:1f53f59a:14a7deea:34ec8c7c

Internal Bitmap : -16 sectors from superblock
    Update Time : Mon May 11 04:08:10 2015
  Bad Block Log : 512 entries available at offset -8 sectors
       Checksum : bd8c1d5b - correct
         Events : 60


   Device Role : Active device 0
   Array State...
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