iSCSI Storage Explained: The Best of RAID, NAS, & SAN
iSCSI and Storage Part 2
Topics:
3: Creating Storage Pool and Simple Volume (RAID – 0)
4: Creating Mirror Volume (RAID – 1)
5: Creating Parity Volume (RAID – 5)
Built-in Disk Management Tools:
• Built-in Disk Management Tools in Windows
– Storage pools.
– Disk Management.
Selecting a Partition Table Format:
GPT
• GPT is the successor of MBR partition table format
• Supports a maximum of 128 partitions per drive
• Can partition a disk up to 18 EB
MBR
• Standard Partition table format since early 1980s
• Supports a maximum of 4 primary partitions per drive
• Can partition a disk up to 2 TB
• Use MBR for disks smaller than 2 TB
• Use GPT for disks larger than 2 TB
What is a Partition?
• A physical disk is sectioned into separate partitions
• A physical disk can have up to three primary partitions and one extended partition
• Extended partitions are subdivided into logical drives
Selecting a File System:
When selecting a file system, consider the differences between FAT, NTFS, and ReFS
FAT provides:
• Basic file system
• Partition size limitations
• FAT32 to enable larger disks
• exFAT developed for flash drives
NTFS provides:
• Metadata
• Auditing and journaling
• Security (ACLs and encryption)
ReFS provides:
• Backward compatibility support for NTFS
• Enhanced data verification and error correction
• Support for larger files, directories, volumes, etc.
What Is Direct Attached Storage?
DAS disks are physically attached to the server
What Is Network Attached Storage?
NAS is storage that is attached to a dedicated storage device
and accessed through network shares
Advantages:
• Relatively inexpensive
• Easy to configure
Disadvantages:
• Slower access times
• Not an enterprise solution
NAS offers centralized storage at an affordable price
What Is a SAN?
SANs offers higher availability with the most flexibility
Advantages:
• Fastest access times
• Easily expandable
• Centralized storage
• High level of redundancy
Disadvantages:
• More expensive
• Requires specialized skills
SANs can be implemented using Fibre Channel or iSCSI
What is iSCSI storage ?
• iSCSI storage is an inexpensive and simple way to configure a
connection to remote disks. Many application requirements dictate
that remote storage connections must be redundant in nature for
fault tolerance or high availability.
• iSCSI transmits SCSI commands over IP networks
Provides the following features:
Network/diskless boot
Server application storage
Heterogeneous storage
Lab environments
What Is the Storage Spaces Feature?
To create a virtual disk, you need the following:
• One or more physical disks
• Storage pool that includes the disks
• Virtual drives that are created with disks from the storage pool
• Disk drives that are based on virtual drives
Virtual drives are not virtual hard disks (VHDs); they should
be considered a drive in Disk Manager
What Is RAID?
RAID means Redundant Array of Inexpensive/Independent Disks.
• RAID combines multiple disks into a single logical unit to provide fault tolerance and performance
• RAID provides fault tolerance by using:
• Disk mirroring
• Parity information
• RAID can provide performance benefits by spreading disk I/O across multiple disks
• RAID can be configured using several different levels
• RAID should not replace server backups
What Is Fault Tolerance?
• The ability to survive hardware failure
• Fault-tolerant volumes provide data redundancy
• Fault-tolerant volumes are not a replacement for backup
Types of RAID Volumes in Windows 2012
• Simple Volume (RAID-0)
• Mirrored Volume (RAID-1)
• Striped With Parity (RAID-5)
What Is a Simple Volume (RAID-0)?
• Minimum - 2 Hard Disks
• Data is written alternately and evenly to two or more disks
• Spanning is available
• Fault Tolerance is not available
• Read & Write Speed is Fast
What Is a Mirrored Volume (RAID-1)?
• Minimum - 2 Hard Disks
• Simultaneously data will be written to two volumes on two different disks
• Any volume can be mirrored including the system and boot volumes
• Fault Tolerance is available
• Read Speed is Fast & Write Speed is Slow
• 50% overhead
What Is a Striped With Parity (RAID-5) Volume?
• Minimum - 3 Hard Disks
• Data is written alternately and evenly to two or more disks and a parity is written on one disk
• Fault Tolerance is available
• Read & Write Speed is Fast,
What Are Mount Points and Links?
A mount point is a reference to a location on a disk that
enables Windows operating system access to disk resources
• Use volume mount points:
• To mount volumes or disks as folders instead of using drive letters
• When you do not have drive letters available for creating new volumes
• To add disk space without changing the folder structure
A link file contains a reference to another file or directory
• Link options:
• Symbolic file link (or, soft link)
iSCSI Storage Explained | RAID, NAS, and SAN Compared
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