Storage devices are used to store data outside of a computer's main memory. There are different types of storage including primary storage like RAM and cache that is directly accessible by the CPU. Secondary storage like hard disks requires accessing through input/output channels. Tertiary storage uses robotic mechanisms to store data offline. Linux uses disk partitioning to organize storage across physical disks using schemes like MBR and GPT. Logical volumes and RAID provide additional abstraction and redundancy. Network storage solutions like NAS export file systems over a network while SANs export block storage using protocols like Fibre Channel and iSCSI.

1. Storage Management
Kasun Rathnayaka
BSc Eng,AM(SL),RHCE,RHCSA,CCIP,CCNA

2. Why we need Storage devices?
What is Storage devices ?
How it works?
How it Manage ?
Do You Know ?

3. Example : Human mind

4. Computer Storage

5. Storage Types
●
Primary storage
– Internal memory , main memory
– Directly access to CPU
– RAM
– Processor registers
●
Hold word (32 or 64 bit)of data
●
addressed by mechanisms other than main
memory and can be accessed more quickly
– Processor cache(L1/L2/L3)
●
intermediate stage between ultra-fast registers and
much slower main memory

6. Storage Types

7. Example
Working example with Linux OS

8. Disk Partitioning - Linux
●
Linux still uses MS-DOS partition table for disks less than 2TB in size.
●
It also has GPT (Guide Partition table) to be used with larger SCSI/SAS
disks
●
MS-DOS partition table uses MBR (Master Boot Record)
●
MBR
– Size of MBR is 512 bytes
– MBR keeps
●
Boot Loader
– GRUB stage 1 (Linux)
– NTLDR (Windows)
●
Primary partition table (As a data structure :linked list)

9. Disk Partitioning - Linux
* AA55 or Magic Number
crafted at the time of manufacturing
* 0-446 bytes are occupied by the
boot loader
* 64 bytes are used by the primary
partition table

10. GPT
GPT allocates 64 bits for logical block
addresses and therefore allows a
maximum partition size of 2^(64)−1
sectors

11. Storage Types
●
Secondary Storage
– External memory
– Differs from primary storage in that it is not directly accessible by the
CPU
– The computer usually uses its input/output channels to access
secondary storage and transfers the desired data using intermediate
area in primary storage
●
Tertiary Storage
– involves a robotic mechanism
– Mount in mass storage media
●
Off line Storage
– Not control in processing Unit

12. Oh!

13. Problems
1.Dynamic resizing is not possible or requires third party tools.
2. Maximum size of a file system is limited by the size of the
largest physical disk available.
3. Creating a snapshot (point in time backup) of the file system
on-line (at run time) is not possible.
4. Number of partitions are limited by the kernel. For example an
SCSI disk can have maximum 15 partitions while an IDE disk can
have 63 partitions.

14. Logical Volume
• Abstraction layer between the physical disks and file systems
• Resize(extend or reduce) easily
• Use discontiguous disk space spanning over multiple disks
allowing to create file systems larger than the physical disks
available.
• Allow point in time backup of file system called snapshots.

15. Logical Volume

16. RAID
 Redundant Array of Inexpensive Disks
 Basic idea is to connect multiple disks together to
provide
 large storage capacity
 faster access to reading data
 redundant data
 Many different levels of RAID systems
 differing levels of redundancy, error checking,
capacity, and cost

17. RAID 0
• Often called striping
• Break a file into blocks of data
• Stripe the blocks across disks
in the syste
• no redundancy or error
detection

18. RAID 1
• A complete file is stored on a
single disk
• A second disk contains an exact
copy of the file
• Provides complete redundancy of
data
• Read performance can be
improved
- file data can be read in parallel
• Write performance suffers
- must write the data out twice
• Most expensive RAID
implementation
-requires twice as much storage
space

19. RAID 3
• One big problem with
Level-1,2 are the disks
needed to detect which
disk had an error
• Modern disks can already
determine if there is an
error
-using ECC codes with
each sector
• So just need to include a
parity disk

20. RAID 5,10

21. Network Storage

22. Network Storage
●
Store and Share data access the Network
●
Mainly to common types
– SAN
• Storage Area Network
• Exports block devices via FC (Fiber Channel) and iSCSI
protocols
– NAS
• Network-attached storage
• Exports file systems (as folders) via NFS and CIFS
protocols

23. Network-Attached Storage

Mainly use File sharing

Not use for server-centric system( ex:email,file management)

Can user multiple NAS devices

Contain one or more disks, often arranged into logical, redundant storage
containers or RAID arrays

The protocol used with NAS is a file based protocol such as NFS, Samba
or Microsoft's Common Internet File System (CIFS)

Multiple Operating system on the device such as Celerra on EMC's
devices or NetOS on NetApp NAS devices

The performance depends on cached memory (the equivalent of RAM)
and network interface overhead

24. NAS:Advantage
●
NAS allows multiple server access through a file-based
protocol.
●
implement simple and low cost load-balancing and fault-
tolerant systems.
●
For example:
●
Corporate e-mail system with multiple, load-balanced
webmail servers
●
Load-balanced web servers access the same contents
from NAS storage

25. NAS:Disadvantage
●
local network will slow down the resulting access time.
●
backup solution is more expensive than the storage solution.
●
Not support in advance storage environment.

26. NAS
✔
Heterogeneous Environment
✔
Centralized Storage
✔
Low Performance
✔
Limited scalability
✔
Network Congestion during backups & Restore
✔
Ethernet Limitations

27. Example
NAS :Samba,NFS

28. Storage Area Network
●
Centralizing data storage operation
●
Primarily used to make storage devices, such as disk
arrays, tape libraries, and optical jukeboxes
●
Administrating all of the storage resources in high-
growth and mission-critical environments can be
daunting and very expensive
●
SANs can be based upon several different types of
high-speed interfaces
●
Fibre Channel
●
iSCSI interfaces

29. FC vs iSCSI

30. FC vs iSCSI
FC SAN iSCSI SAN
Fiber network Ethernet network
High cost Lower than FC
Bandwidth 1,2,4,8,10,1 6Gbps Bandwidth 1,2,4,10Gbps
High performances Low than FC,but good for small
company
FC SANs use SCSI and FC drives for
their high performance and reliability.
iSCSI SANs commonly use SATA
and SAS drives, primarily for their low
cost and large capacity

31. Zoning and VSAN
• partitioning of a Fibre Channel Fabric into smaller subsets to
restrict interference
• Add security, and to simplify management
• SAN should only be allowed access to a controlled subset of
these devices/ports
• Zoning is different from VSAN, in that each port can be a
member of multiple zones, but only one VSAN.
• VSAN (similarly to VLAN) is in fact a separate network.

32. Zoning types
 Soft zoning
 implemented in software
 uses filtering implemented in fibre channel switches to prevent ports from being seen
from outside of their assigned zones.
 Connect to any port on the switch
 Soft Zoning means that the FC switch will place a host WWN in a zone, without dealing
with the port numbers they’re connected to in the FC switchhard zoning
 Hard zoning
• implemented in hardware.
• physically blocks access to a zone from any device outside of the zone.
• Usually hard zoning is used when using VLANs. You would associate a port into a zone

33. Zoning types

34. SAN
➢
Centralized Storage Management
➢
High Degree of Fault Tolerance
➢
Best and superior performance
➢
Storage Consolidation
➢
Fast and efficient backups and restores
➢
Dynamic Scalability
➢
Expensive solution for small setups