Storage Management on Linux are classified into three types:

  1. DAS(Direct attached storage)
  2. NAS (Network attached storage)
  3. SAN(Storage Area?Network)
1. DAS(Direct?attached storage)
  • Direct?attached storage (DAS) refers to a digital storage system directly connected to a server or digital computer, while not a storage network in between.
  • It’s a retronym, principally wont to differentiate non?networked storage from SAN and NAS
  • A typical DAS system is created of a knowledge device connected on to a laptop through a host bus adapter (HBA).
  • Between those 2 points there’s no network device (like hub, switch, or router), and this is often the most characteristic of DAS.
  • the most protocols used for DAS connections are ATA, SATA, eSATA SCSI, SAS, and Fibre Channel.
2. NAS (Network?attached storage)
  • Network?attached storage (NAS), in distinction to SAN, uses file?based protocols like NFS or SMB/CIFS wherever it’s clear that the storage is remote, associate degreed computers request some of an abstract file instead of a disk block.
3. SAN(Storage?Area?Network)
  • A Storage Area Network (SAN) could be a dedicated network that has access to consolidated, block level information storage.
  • SANs are primarily wont to build storage devices, like disk arrays, tape libraries, and optical jukeboxes, accessible to servers in order that the devices appear as if regionally connected devices to the package.
  • A SAN generally has its own network of storage devices that square measure typically not accessible through the native space network by different devices. the price and quality of SANs born within the early 2000s to levels permitting wider adoption across each enterprise and tiny to medium sized business environments.

Features of SAN

  • Sharing storage typically simplifies storage administration
  • Adds flexibility since cables and storage devices don’t ought to be physically stirred to shift storage from one server to a different
  • Ability to permit servers else from the SAN itself.
  • SANs conjointly tend to modify more practical disaster recovery processes.

Linux tgtadm: Setup iSCSI Target ( SAN )

iSCSI target (server)
  • Storage resource located on an iSCSI server known as a “target”.
  • An iSCSI target usually represents nothing but hard disk storage.
  • As with initiators, software to provide an iSCSI target is available for most mainstream operating systems.
iSCSI initiator (client)
  • An initiator functions as an iSCSI client.
  • An initiator typically serves the same purpose to a computer as a SCSI bus adapter would, except that instead of physically cabling SCSI devices (like hard drives and tape changers), an iSCSI initiator sends SCSI commands over an IP network.

SAN Server Installation and Configuration

Step-I(Install the iscsi pkgs & start services)
# yum install *scsi*
# service tgtd start
Step-II(creates a target with id 1)
# tgtadm --lld iscsi --op new --mode target --tid 1 –T iqn.2011-09.com.galaxy:storage.disk1.linux.sys1.xyz
Step-III(To view the current configuration)
# tgtadm --lld iscsi --op show --mode target
Step-IV(Add a logical unit to Target)
# tgtadm --lld iscsi --op new --mode logicalunit --tid 1--lun 1 -b /dev/sdb1
Step-V(To view the details)
# tgtadm --lld iscsi --op show --mode target
Step-VI(To enable the target to accept any initiators)
# tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL

SAN Client Side Configuration

Step-I(To discover targets at a given IP address)
# iscsiadm --mode discovery --type sendtargets--portal <iscsi_server_ip>
Step-II(To check at client run fdisk and mount)
# fdisk -l
# mkdir /mnt/clientsan
# mount /dev/sdb1 /mnt/clientsan

That’s all for now.

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