chetanstorage

8/7/2019 chetanSTORAGE

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LOVELY PROFESSIONAL UNIVERSITY

Design Problem: #2

Course Title: STORAGE Management concepts

And

Administration

Course No: CSE554

Name of the faculty member: Mr. NAVDEEP KAUR SANDHU

Submitted By:CHETAN

SHARMA

SECTION: A17T1

ROLL NO. RA17T1A11

REGN. NO. 5050070015



(a) How can a block-level virtualization implementation be used as a data migration tool?

Sol: - Data migration is basically data movement taking data from one folder, partition, disk or

disk subsystem, and then placing that data into another physical location. In many cases, data is

migrated to accommodate tiered storage, often as part of a data classification initiative.

As we know that in case of block level virtualization there is a virtualization engine which is

responsible for handling the back end data migration. So, this migration of data enables LUNs to

remain online and accessible while data is being migrated.

Hence it is the virtualization engine that helps the block level virtualization to be implemented

and used as a data migration tool.

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(b) Explain how data migration will be accomplished and discuss the advantages of usingthis method for storage. Compare this method to traditional migration methods.

Sol: - Accomplishment of data migration: - In case of block-level virtualization there is a

virtualization engine which is responsible for handling the back end migration of data and this

migration of data enables the LUNs to remain online and accessible while data is being

migrated. Here during data migration we do not require any physical changes because the host of

the data is still pointing towards the same virtual targets on the virtualization device.

Data migration operation: - Whenever an I/O request from any host arrives at the DPC, it

handles the I/O request and then maps it to the appropriate virtual target. In some of the

exceptional cases, if the command is a SCSI enquiry about the device or an I/O for which the

DPC does not have the migration information, the CPC handles the request.

If a new storage array is added to the intelligent switch the CPC discovers the new array and

updates the migration information to put that new array into use. When the migration and

mapping is done the I/O gets redirected to the new storage location. Similarly if an old array

needs to be removed, the CPC issues another set of instructions to migrate the data from an old

array to a new array. The DPC copies the data online and the old array can be moved out without

causing any inconvenience to the user or to the system as a whole.

Advantages of using data migration method for storage: -

1. This data migration method also supports local and remote replication or duplication

functionality.



2. This data migration method also utilizes full fabric bandwidth for the implementation

of high speed I/O processing.

3. This data migration method provides separate data and control paths for easy

management and faster I/O processing.

Comparison with traditional methods: - Traditional migration methods do not use the

fundamentals of the block-level virtualization and also do not support local or remote duplication

of data this is because these systems lay stress on cost constraints associated with the disk and

storage spaces.

Also in case of traditional methods full fabric bandwidth is not properly utilized and hence they

are slow in processing the I/O requests.

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(c) Which method of migration will you use? Why you are recommending this particular

method.

Sol: -

Some methods of data migration are as: -

Disk to Tape Data Migration: - Magnetic tape is the ideal storage medium for businesses

with a large amount of data and organizations that require a highly organized data archiving

processes. With disk to tape data migration, data is transferred from the original hard disk to

a tape drive.

Disk to tape data migration can be a lengthy process and can cause problems for 24 hour

operations or organizations where the necessary time needed to backup data is longer than

the data backup window. In this case, disk to disk to tape data migration is ideal.

Disk to Disk to Tape Data Migration: - With disk to disk to tape data migration, data is

first instantly mirrored on a secondary disk drive and then written to magnetic tape.

Disk-Storage: - Disk storage is the process of moving data to a secondary hard disk. Disk

storage is more costly than magnetic tape, but works well for organizations with limited data



storage requirements that use disk storage for the purpose of keeping backup data for disaster

recovery.

So, among these three data migration methods we will choose Disk to Disk to TapeMigration because this process eliminates the problem of short or non existent back up

window while still affording the benefits of magnetic tape storage.

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PART – B

The online order department of lovely sweets promises customer access to the online placement

of orders table between 9:00 am and 4:00 pm from Monday to Friday. It updates the table every

day at 8:00 am with a feed from the mainframe system. The update process takes 35 minutes tocomplete. On Thursday, due to a database corruption, the order table could not be updated. At

9:05 am, it was established that the table had errors. A rerun of the update was done and the table

was recreated at 9:45 am. Verification was run for 15 minutes and the order table became

available to the branches. What was the availability of the order table for the week in which this

incident took place, assuming there were no other issues?

Sol: - Given that the customers can have access to the order tables from Monday to Friday

between 9:00 am to 4:00 pm.

No. of hours the order tables are available to customers on Monday = 7 hours or 420 minutes.

No. of hours the order tables are available to the customers on Tuesday = 7 hours or 420

minutes.

No. of hours the order tables are available to the customers on Wednesday = 7 hours or 420

minutes.

No. of hours the order tables are available to the customers on Friday = 7 hours or 420

minutes.

Also given that an error has occurred on Thursday.

For initial five minutes i.e. from 9:00 am to 9:05 am the tables are available.



At, 9:05 am it was established that the table had errors. A rerun of the update was done and

the table was recreated at 9:45 am.

Therefore time taken to recreate the table on Thursday from (9:05 am to 9:45 am) = 40

minutes.

Time taken to verify the tables = 15 minutes.

Now,

No. of hours order tables are available to the customers on Thursday = 6 hours and 5 minutes

or 365 minutes.

Now let us calculate the total system uptime from Monday to Friday = (uptime for Monday

+ uptime for Tuesday + uptime for Wednesday + uptime for Thursday + uptime for

Friday)

Total system uptime = (420 + 420 + 420 + 365 + 420)

Hence the order tables remain available for 2045 minutes or 34.08 hours from Monday to

Friday.

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Total s stem u time = 2045 minutes or 34.08 hours.

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