CS414 Operating Systems - Homework 5
General Instructions.
You are expected to work alone on this assignment.
Due: (Tues) April 22, 10am.
No late assignments will be accepted.
Submit your solution using CMS.
Prepare your solution using Word (.doc) or some ascii editor (.txt), as follows:
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Use 10 point or larger font.
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Start each problem's solution on a new page.
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Use at most 1 page per problem.
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Consider a UNIX-like file system that uses inodes, where
each inode contains 6 direct pointers, 3 indirect-pointers,
and 3 double-indirect pointers.
All blocks are 1K bytes and pointers are 4 bytes.
What is the largest file that can be accomodated?
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An alternative to implementing a file system with directories is to
regard a path name as monolithic and support a single, flat, name space.
That is, a/b/c would
simply be a name that happens to have 2 slashes in it, where slashes
have no special significance. We might
implement such a file system by having a single hash-table in place
of the usual directory structure. Hashing
the name (e.g., "a/b/c") yields an entry in the hash table, and that
entry contains the address of the inode for file a/b/c.
(Ignore the possibility of hash table collisions, since these can be dealt with in
the usual way.)
Compare this new implementation with the
usual approach of having file names be paths in a directed graph (of
directories).
What (if anything) is sacrificed and what (if anything)
is gained with each approach?
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Consider a RAID comprising 4 mirrored disks.
Discuss how the performance of this storage system would compare to a single disk.
Give your answer in terms of the performance
properties of the disks (e.g., seek time, transfer time, etc)
and the workload (e.g., numbers or accesses).
Include a discussion of the impact that might be observed
from various schemes a RAID controller might use reorder and/or
route I/O requests to the specific disks comprising the RAID.