Redhat Linux Interview Questions and Answers part 10

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Q: – which utility or command is used for creating software RAID’s for RHEL5?

mdadm

Q: – Can we create software RAID during Linux installation?

Yes, we can create Software RAID during Linux Installation by “Disk Druid”

Q: – Explain /proc filesystem?

/proc is a virtual filesystem that provides detailed information about Linux kernel, hardware’s and running processes. Files under /proc directory named as Virtual files. Because /proc contains virtual files that’s why it is called virtual file system. These virtual files have unique qualities. Most of them are listed as zero bytes in size. Virtual files such as /proc/interrupts, /proc/meminfo, /proc/mounts, and /proc/partitions provide an up-to-the-moment glimpse of the system's hardware. Others, like the /proc/filesystems file and the /proc/sys/ directory provide system configuration information and interfaces.

Q: – Can we change files parameters placed under /proc directory?

Yes,to change the value of a virtual file, use the echo command and a greater than symbol (>) to redirect the new value to the file. For example, to change the hostname on the fly, type:
echo www.nextstep4it.com > /proc/sys/kernel/hostname

Q: – Explain RAID 1?

RAID Level 1 is based on Mirroring technique. Level 1 provides redundancy by writing identical data to each member disk of the array. The storage capacity of the level 1 array is equal to the capacity of one of the mirrored hard disks in a Hardware RAID or one of the mirrored partitions in a Software RAID. RAID 1 provides redundancy means good protection against disk failure. In RAID 1 write speed is slow but read speed is good.

Q: – Explain RAID 5?

RAID Level 5 is based on rotating parity with striping technique. RAID-5 stores parity information but not redundant data (but parity information can be used to reconstruct data). The storage capacity of Software RAID level 5 is equal to the capacity of the member partitions, minus the size of one of the partitions if they are of equal size. The performance of RAID 5 is based on parity calculation process but with modern CPUs that usually is not a very big problem. In RAID 5 read and write speeds are good.

Q: – Which kernel module is required for Software RAID?

“md” module

Q: – What is the role of chunk size for software RAID?

Chunk size is very important parameter on which RAID performance based.
We know stripes go across disk drives. But how big are the pieces of the stripe on each disk? The pieces a stripe is broken into are called chunks.To get good performance you must have a reasonable chunk size.

For big I/Os we required small chunks and for small I/Os we required big chunks.

Q: – What is the use of sysctl command?

The /sbin/sysctl command is used to view, set, and automate kernel settings in the /proc/sys/ directory.

Submitted By:-Parveen Kumar            Email-ID: – parveen.antil@gmail.com

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