Redhat Linux Interview Questions and Answers part 8

Q: – What is the difference between ext2 and ext3 file systems?

The ext3 file system is an enhanced version of the ext2 file system.

The most important difference between Ext2 and Ext3 is that Ext3 supports journaling.
After an unexpected power failure or system crash (also called an unclean system shutdown), each mounted ext2 file system on the machine must be checked for consistency by the e2fsck program. This is a time-consuming process and during this time, any data on the volumes is unreachable.
The journaling provided by the ext3 file system means that this sort of file system check is no longer necessary after an unclean system shutdown. The only time a consistency check occurs using ext3 is in certain rare hardware failure cases, such as hard drive failures. The time to recover an ext3 file system after an unclean system shutdown does not depend on the size of the file system or the number of files; rather, it depends on the size of the journal used to maintain consistency. The default journal size takes about a second to recover, depending on the speed of the hardware.

 Q: – Explain the command "rpm -qf "?

it queries the RPM database for which package owns <filename>. When specifying a file, specify the absolute path of the file.

 Q: – How to verify all installed packages?

rpm -Va

Q: – How Many Run Levels present in Linux?

There are 7 run levels, with each having its own properties.

–   0: Halt the system
–   1: Single-user mode
–   2: Not used
–   3: Multi-user mode with text login
–   4: Not used
–   5: Multi-user mode with graphical login
–   6: Reboot

Q: – Which configuration file is required to change the Run Level of Server or system?

To change the default run level, modify this line.

 Q: – Any idea about ext4 file system?

The ext4 or fourth extended filesystem is a journaling file system developed as the successor to ext3. Ext4 filesystem released as a functionally complete and stable filesystem in Linux with kernel version 2.6.28.

Features of ext4 file system:-

1. Currently, Ext3 supports 16 TB of maximum file system size and 2 TB of maximum file size. Ext4 have 1 EB of maximum file system size and 16 TB of maximum file size.

[An EB or exabyte is 1018 bytes or 1,048,576 TB]
2. Fast fsck check than ext3
3 In Ext4 the journaling feature can be disabled, which provides a small performance improvement.
4. Online defragmentation.
5. Delayed allocation
Ext4 uses a filesystem performance technique called allocate-on-flush, also known as delayed allocation. It consists of delaying block allocation until the data is going to be written to the disk, unlike some other file systems, which may allocate the necessary blocks before that step.

Q: – How to verify the signature of an rpm?

rpm -K test-1.0-1.i386.rpm

Q: – Explain architectures required for RPMs?

noarch Architecture-independent, can run on any architecture
i386   Generic build for a 32-bit x86 system
i586   Sometimes used when building kernels for older x86 processors
Intel® Pentium ® II, Intel Pentium III, Intel Pentium 4, AMD Athlon, and
i686   AMD Duron systems (Most RPMs for these architectures are built using the i386 architecture, with the kernel for these architectures being built with the
i686 for optimal performance.)
x86_64 64-bit processors such as AMD Athlon64, AMD Opteron, and Intel EM64T
ia64   Intel® Itanium
ppc    32-bit IBM® POWER, IBM eServer„ pSeries®, and IBM eServer iSeries
s390x  64-bit IBM eServer System z

Q: – How we create ext3 file system on /dev/sda7 disk?

# mkfs –j /dev/sda7

Submitted By:-Parveen Kumar            Email-ID: –