Storage

Question 1

What are the 3 important storage components of cloud systems

Answer 1

Infrastructure Platform Software

Question 2

What is Redundancy?

Answer 2

Redundancy is a solution to the fault tolerance problemof disks
Redundancy can come in two forms:
Complete Redundancy (Copies)
Partial Redundancy

Question 3

What is Partcial Redundancy?

Answer 3

Error Correcting Codes (ECC)
Detecterrors
Correcterrors
•
Hamming codes
Data bits+ Parity bits= Total bits

Question 4

What are redundancy advantages

Answer 4

Individual disks
Multiple disks

Question 5

What are disadvantages of redundancy

Answer 5

Cost

Slower updates

Greater complexity

Question 6

What are the RAID Levels?

Answer 6

Currently accepted RAID levels:
–
0 : no redundancy striping (just a bunch of disks JBOD)
1 : full copy (mirroring)
10 (said one-zero) : striped mirrors
2 : bit level striping, Hamming-codes / ECC (not used)
3 : byte-interleaved parity
4 : block interleaved parity (more useful variant of RAID3)
5 : rotated block-interleaved parity
6 : double parity (rare)

Question 7

How do Hosts/ Servers connect to disks/arrays?

Answer 7

common methods:
–
Direct Attached Storage→DAS

IDE: simple general purpose bus system
SCSI: higher capacity bus

Network Attached Storage→NAS

Storage Area Networks→SAN

Blocksare primary unit of data
Dedicated network… used primarily for storage

Question 8

What are the cloud storage levels?

Answer 8

Blocks: lowest level of storage and closest to hardware.
Files: collections of datagrouped into files located in folders
Datasets: data organised into table-based, delimited, or record format
Objects: data and its associated metadataorganised as web-based resources

Question 9

What are Network Storage Interfaces?

Answer 9

SCSI for storage blocks (SCSI)
Server Message Block (SMB)
Common Internet File Service (CIFS)SMB v1
Network File System (NFS)

Question 10

How are object storage interfaces accessed?

Answer 10

typically accessed via REST or Web Service based cloud services

Question 11

What query langauages do dateabase storage interfaces support?

Answer 11

Relational Data; SQL, DB@, Oracle, MSSQL, My SQL

Non-relational Data; NoSQL

Question 12

Storage is Virtualized, what features does this help?

Answer 12

Data organisation and management
Support for QoS and SLAs –monitoring
Data migration and load balancing
Data deduplication(improves storage efficiency)
Storage security

Question 13

Datastores can be implemented on what storage?

Answer 13

block-based storage (hard disks / SSDs),

direct-attached storage (DAS),

Fibre Channel, Fibre Channel over Ethernet (FCoE), iSCSI, and remotely accessed using either VMFS or NFS