Data StorageData Storage

Willis KimWillis Kim

14 May 200514 May 2005

Types of storagesTypes of storages

• Direct Attached Storage – storage Direct Attached Storage – storage hardware that connects to a single hardware that connects to a single server server

• Storage Area Network - connects Storage Area Network - connects multiple servers to a pool of storage multiple servers to a pool of storage over a private network over a private network

• Network Attached Storage - connects Network Attached Storage - connects multiple servers to a pool of storage multiple servers to a pool of storage over a network over a network

Direct Attached StorageDirect Attached Storage

• Personal storage device using fire Personal storage device using fire wire or USB 2.0wire or USB 2.0– USB 1.0 is very slow for large-scale back USB 1.0 is very slow for large-scale back

upup

• SCSI disk arraySCSI disk array– PCI SCSI controllerPCI SCSI controller– Supports RAIDSupports RAID

RAIDRAID

AdvantagesRAID 0 offers great performance, both in read and write operations. There is no overhead caused by parity controls.All storage capacity can be used, there is no disk overhead.The technology is easy to implement.DisadvantagesRAID 0 is not fault-tolerant. If one disk fails, all data in the RAID 0 array are lost. It should not be used on mission-critical systems.UseRAID 0 is ideal for non-critical storage of data that have to be read/written at a high speed

In a RAID 0 system, data are split up in blocks that get written across all the drives in the array. By using multiple disks (at least 2) at the same time, RAID 0 offers superior I/O performance. This performance can be enhanced further by using multiple controllers, ideally one controller per disk.

AdvantagesRAID 1 offers excellent read speed and a write-speed that is comparable to that of a single disk.In case a disk fails, data do not have to be rebuild, they just have to be copied to the replacement disk.RAID 1 is a very simple technology.DisadvantagesThe main disadvantage is that the effective storage capacity is only half of the total disk capacity because all data get written twice.Software RAID 1 solutions do not always allow a hot swap of a failed disk (meaning it cannot be replaced while the server keeps running). Ideally a hardware controller is used. UseRAID-1 is ideal for mission critical storage. It is also suitable for small servers in which only two disks will be used. Available on Windows Server (2000 and 2003)

Data are stored twice by writing them to both the data disk (or set of data disks) and a mirror disk (or set of disks) . If a disk fails, the controller uses either the data drive or the mirror drive for data recovery and continues operation. You need at least 2 disks for a RAID 1 array.

Advantages

RAID-3 provides high throughput (both read and write) for large data transfers. Disk failures do not significantly slow down throughput.

Disadvantages

This technology is fairly complex and too resource intensive to be done in software. Performance is slower for random, small I/O operations.

On RAID 3 systems, datablocks are subdivided (striped) and written in parallel on two or more drives. An additional drive stores parity information. You need at least 3 disks for a RAID 3 array.Since parity is used, a RAID 3 stripe set can withstand a single disk failure without losing data or access to data.

Advantages

Read data transactions are very fast while write data transaction are somewhat slower (due to the parity that has to be calculated).

Disadvantages

Disk failures have an effect on throughput, although this is still acceptable.

Like RAID 3, this is complex technology.

Use

RAID 5 is a good all-round system that combines efficient storage with excellent security and decent performance. It is ideal for file and application servers.

RAID 5 is the most common secure RAID level. It is similar to RAID-3 except that data are transferred to disks by independent read and write operations (not in parallel). The data chunks that are written are also larger. Instead of a dedicated parity disk, parity information is spread across all the drives. You need at least 3 disks for a RAID 5 array.

RAID 10 combines the advantages (and disadvantages) of RAID 0 and RAID 1 in a single system. It provides security by mirroring all data on a secondary set of disks (disk 3 and 4 in the drawing below) while using striping across each set of disks to speed up datatransfers.

What is SAN?What is SAN?

• A SAN, or storage area network, is a dedicated A SAN, or storage area network, is a dedicated network that is separate from LANs and WANs.  It network that is separate from LANs and WANs.  It generally serves to interconnect the storage-generally serves to interconnect the storage-related resources that are connected to one or related resources that are connected to one or more servers.  It is often characterized by its high more servers.  It is often characterized by its high interconnection data rates (Gigabits/sec) between interconnection data rates (Gigabits/sec) between member storage peripherals and by its highly member storage peripherals and by its highly scalable architecture.  Though typically spoken of scalable architecture.  Though typically spoken of in terms of hardware, SANs very often include in terms of hardware, SANs very often include specialized software for their management, specialized software for their management, monitoring and configuration.monitoring and configuration.

SAN TopologySAN Topology

SAN ExampleSAN Example

Deployed NAS 1

Deployed NAS 2

Fibre Channel Switches

E-mail Server 1

E-mail Server 2

E-mail Server 3 Fibre Channel SwitchesStorage Area Network

PA

CA

F L

AN

Tier 1 Storage

LAN

Network

Tier 2 & 3 Storage - Clariion

NAS

What is NAS?What is NAS?

• Network-attached storage (NAS) is a Network-attached storage (NAS) is a concept of shared storage on a network. It concept of shared storage on a network. It communicates using Network File System communicates using Network File System (NFS) for UNIX+ environments, Common (NFS) for UNIX+ environments, Common Internet File System (CIFS) for Microsoft Internet File System (CIFS) for Microsoft Windows environments, FTP, http, and other Windows environments, FTP, http, and other networking protocols. NAS brings platform networking protocols. NAS brings platform independence and increased performance independence and increased performance to a network, as if it were an attached to a network, as if it were an attached appliance. appliance.

NAS TopologyNAS Topology

NAS ExampleNAS Example 42 U

Network Appliance Solution, 20 TB

Network

Raw disk space =

10 shelfs x 14 disks per shelf x 144 GB per disk

= 20,160 GB ~ 20 TB (raw)

Useable space =

10%(OS) +20% (Snapreserve + Parity drives + Spare Drives)

NAS(File)

Complete Storage TopologyComplete Storage Topology

Departmental

iSCSI

Enterprise

SAN(Block)

FibreChannel

Enterprise

DedicatedEthernet

SAN NASDepartmental

CorporateLAN

Network ApplianceNetwork Appliance

Common Internet File Common Internet File SystemSystem• As known as Server message block As known as Server message block

(SMB)(SMB) is a is a network protocolnetwork protocol mainly mainly applied to share files, printers, serial ports, applied to share files, printers, serial ports, and miscellaneous communications and miscellaneous communications between nodes on a network. It is mainly between nodes on a network. It is mainly used by used by Microsoft WindowsMicrosoft Windows equipped equipped computers.computers.

http://en.wikipedia.org/wiki/CIFShttp://en.wikipedia.org/wiki/CIFS

Network Appliance – RAID 4Network Appliance – RAID 4

NAS Demonstration NAS Demonstration TopologyTopology

VDSL via POTS

Router and Wireless Access Point 802.11b/g192.168.1.1 (gateway)

SeoulCC@USOVDSL modem

ComputerDHCP

Wireless Access Point 802.11g192.168.1.1

Linksys

192.168.1.225

NAS DemonstrationNAS Demonstration

• Sharing file using CIFSSharing file using CIFS– Command LineCommand Line– RAID 4RAID 4

• Failure recoveryFailure recovery– Power supplyPower supply– DiskDisk

Bonus StuffBonus Stuff

• LookoutLookout

• Google DesktopGoogle Desktop