File-System
Question 1 |
Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.
4 |
Question 1 Explanation:
Question 2 |
A file system with 300 GByte disk uses a file descriptor with 8 direct block addresses, 1 indirect block address and 1 doubly indirect block address. The size of each disk block is 128 Bytes and the size of each disk block address is 8 Bytes. The maximum possible file size in this file system is
3 KBytes | |
35 KBytes | |
280 KBytes | |
dependent on the size of the disk |
Question 2 Explanation:
It’s given disk block is of size 128B.
So, one direct block addressing will point to 8 disk blocks = 8*128 B = 1 KB
Singly Indirect block addressing will point to 1 disk block which has 128/8 disc block addresses = (128/8)*128 B = 2 KB
Doubly indirect block addressing will point to 1 disk block which has 128/8 addresses to disk blocks which in turn has 128/8 addresses to disk blocks = 16*16*128 B = 32 KB
Maximum possible file size = 1 KB + 2 KB + 32 KB = 35 KB
So, one direct block addressing will point to 8 disk blocks = 8*128 B = 1 KB
Singly Indirect block addressing will point to 1 disk block which has 128/8 disc block addresses = (128/8)*128 B = 2 KB
Doubly indirect block addressing will point to 1 disk block which has 128/8 addresses to disk blocks which in turn has 128/8 addresses to disk blocks = 16*16*128 B = 32 KB
Maximum possible file size = 1 KB + 2 KB + 32 KB = 35 KB
Question 3 |
The data blocks of a very large file in the Unix file system are allocated using
contiguous allocation
| |
linked allocation
| |
indexed allocation | |
an extension of indexed allocation
|
Question 3 Explanation:
An Unix file system can utilizes an extension of indexed allocation. Because it uses direct blocks, single indirect blocks, double indirect blocks and triple indirect blocks.
Question 4 |
In the index allocation scheme of blocks to a file, the maximum possible size of the file depends on
the size of the blocks, and the size of the address of the blocks. | |
the number of blocks used for the index, and the size of the blocks. | |
the size of the blocks, the number of blocks used for the index, and the size of the address of the blocks. | |
None of the above |
Question 4 Explanation:
No. of addressable blocks using one Index block (A) = Size of block/Size of block address.
No. of block addresses available for addressing one file(B) = No. of Maximum blocks we can use for the Index * No. of addressable blocks using one Index block(A)
Size of File = B * Size of Block
No. of block addresses available for addressing one file(B) = No. of Maximum blocks we can use for the Index * No. of addressable blocks using one Index block(A)
Size of File = B * Size of Block
Question 5 |
I/O redirection
implies changing the name of a file | |
can be employed to use an existing file as input file for a program | |
implies connection 2 programs through a pipe | |
None of the above
|
Question 5 Explanation:
Redirection is known as capturing output from a file, command, program (or) even code block within a script and sending it as input to another file, command, program (or) script.
There are 5 questions to complete.