IN2213-G8_W21_As CopyLook UpSelect AllShare...4. Suppose you use RAID level 0+1 (striping and mirroring) to do blockwise striping over 4 disks,and you have mirrored the data on another 4 disks. Under optimal circumstances (i.e., equaldistribution of requests, perfect load balancing), the number of block read accesses allowed bythe RAID system would beExplain your answer. a. the same as for a single diskb. two times higher than a single diskc. four times higher than a single diskd. eight times higher than a single disk IN2213-G8_W21_As CopyLook UpSelect AllShare...4. Suppose you use RAID level 0+1 (striping and mirroring) to do blockwise striping over 4 disks,and you have mirrored the data on another 4 disks. Under optimal circumstances (i.e., equaldistribution of requests, perfect load balancing), the number of block read accesses allowed bythe RAID system would beExplain your answer. a. the same as for a single diskb. two times higher than a single diskc. four times higher than a single diskd. eight times higher than a single disk

RAID is defined as a Redunt Array of Independent Disks It contains number of disks for processing…

A. Suppose you use RAID level 0+1 (striping and mirroring) to do blockwise striping over 4 disks, and you have mirrored the data on another 4 disks. Under optimal circumstances (i.e., equal distribution of requests, perfect load balancing), the number of block read accesses allowed by the RAID system would be _. Explain your answer. a. the same as for a single disk b. two times higher than a single disk c. four times higher than a single disk d. eight times higher than a single disk

A. Suppose you use RAID level 0+1 (striping and mirroring) to do blockwise striping over 4 disks, and you have mirrored the data on another 4 disks. Under optimal circumstances (i.e., equal distribution of requests, perfect load balancing), the number of block read accesses allowed by the RAID system would be _. Explain your answer. a. the same as for a single disk b. two times higher than a single disk c. four times higher than a single disk d. eight times higher than a single disk

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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A power failure that occurs while a disk block is being written could result inthe block being only partially written. Assume that partially written blocks canbe detected. An atomic block write is one where either the disk block is fullywritten or nothing is written (i.e., there are no partial writes). Suggest schemesfor getting the effect of atomic block writes with the following RAID schemes.Your schemes should involve work on recovery from failure.a. RAID level 1 (mirroring)b. RAID level 5 (block interleaved, distributed parity)
A power failure that occurs while a disk block is being written could result inthe block being only partially written. Assume that partially written blocks canbe detected. An atomic block write is one where either the disk block is fullywritten or nothing is written (i.e., there are no partial writes). Suggest schemesfor getting the effect of atomic block writes with the following RAID schemes.Your schemes should involve work on recovery from failure. RAID level 1 (mirroring)
2. Consider a file with a secondary dense index structure on a non-ordering key field where 120,000 records stored on a disk with block size of 2048 bytes. Length of every record is of fixed and un-spanned. Record size is 150 bytes. Also consider, every record of index file is 20 bytes long. Now assume every block access requires 0.015 second. Can you measure the average improvement in time?
100: T1 update C (steal) 110: T2 update A 115: Begin_checkpoint 120: T2 update A (steal) 130: T1 update C 140: End_checkpoint 150: T1 commit 160: T2 update C (steal) 170: crash, restart 1. Consider the log above produced by WAL under No-force and Steal policy. With (steal), the update is forced to the disk, and without (steal), the update is made to the memory frame only. The initial value of each page (A and C) is 0 and each update increases the page value by 1. Explain what happens at each line from 100 to 160 during normal execution.
EXPLAIN WHERE YOU FIND THE The database has 500000 million records A database must store an employee table consisting of 100000records each of which is 80byteslong. Answer the following questions by assuming these congurations/parameters: B = 512bytes,interblock gap size G = 128bytes, numberof blockspertrack = 256, numberof trackspersurf ace =400. The disk has 8 platters each with two heads (only one head can read at a time of all 16 heads),rotates at 7200rpm, has a track − to − trackseektime(m) of 1ms, s = 12ms, r = 4.16ms, andbtt = 0.03255ms. 1. How many records can be stored per block (blocking factor) using spanned and unspannedcongurations?2. What is the utilization (%) for the unspanned conguration?3. If the le is physically ordered, what is the average time in milli second to read a record ineach conguration?
What are RAID (0 + 1) and (1 + 0)? Explain the difference between them.
A file system with 300 GByte uses a file descriptor with 8 direct block address. 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. Find the maximum possible file size in this file system.
Consider a file system on a disk that has both logical and physical block sizes of 512 bytes. Assume that the information about each file is already in memory. For each of the three allocation strategies (contiguous, linked, and indexed), answer the following question: If we are currently at logical block 10 (the last block accessed was block 10) and want to access logical block 4, how many physical blocks must be read from the disk?
(e) A file is protected by a random password consisting of n binary bits. All password combinations are equally probable. To access the file we need the correct password. The process of applying the password to the file takes 10ms regardless of the value of n. Brute force attack is always a viable basic strategy for guessing a password. To ensure that the file remains sufficiently secure, we need to ensure that there is no more than a 1% chance over 30 days that the password is guessed by a hacker program utilizing brute force working 24 hours a day, 7 days a week. How many bits should be specified for the password?
Consider a file whose size varies between 2KB and 8MB during its lifetime. It is required that the file be accessible in the face of corrupted disk blocks. State, with reasons, whether or not the following block allocation schemes will be appropriate for implementing the file storage: contiguous, linked and table/indexed
. Q: In this problem you are to compare reading a file using a single-threaded file server and a multithreaded server. It takes 15 msec to get a request for work, dispatch it, and do the rest of the necessary processing, assuming that the data needed are in a cache in main memory. If a disk operation is needed, as is the case one-third of the time, an additional 75 msec is required, during which time the thread sleeps. How many requests/sec can the server handle if it is single threaded? If it is multithreaded?
stored on a disk. Suppose that we have an ordered file of 30,000 neconots with block size. 1024 Bytes. File records are of fixed length and are of size un-spanned a primary index •100 bytes on the key a block pointer of size 6- bytes. to search for a record wing and suppose that we have created field of the file of size 9 bytes and then find the aug no. of blocks. with and without index?