NAS/SAN & ISCSI Help

**spookshow** · 22-09-2010

The space available inside a PC is limited. In addition, the average user does not perhaps want to get their hands dirty in order to add a hard drive configuration that runs in and risking the damage. In fact, the solution of the SIN is an alternative that is gaining credibility every day, and despite a relatively high cost.

There are variety of iSCSI servers, many of them are proprietary and some of the companies that market include IBM, Sun, HP, etc. As we see, are big companies, and therefore the price of their solutions is usually quite big too. As we do not want to pay others and we are sure that we understand very well the iSCSI technology (assuming they read the previous post in this blog ) They do not need this kind of support, we will install our SAN or Storage Area in good Area Network.

iSCSI is an extension of SCSI, which is not nothing but a protocol for device communication. SCSI is typically used in devices physically connected to a host or server, such as hard drives, CD or tape devices. In iSCSI, the SCSI commands that manage the device, sent over the network. So that instead of having a SCSI disk physically connected to our team, we connect through the network. But that does not already exist with Samba or NFS. No, these systems work by importing a file system via the network. iSCSI hardware device imports the entire network, so that the client is detected as a SCSI device. All this is done transparently, as if the disc is connected directly to hardware.

The simple answer is to centralize and disk storage server information. For example we could have an iSCSI server with 1 Terabyte (1024 Gigabytes) of storage to centralize all storage devices in our network. On the other hand we could have our servers: mail, ftp, web, samba, all without disks or partitions for data. Data disks be connected via iSCSI over the network and if any of our servers were to fall or to maintain them would have the information on a disc that could be "plugged" by the network. So if we have a secondary server, we only have to connect the iSCSI disk and we will walk in a very short service time.

SCSI disks typically provide excellent transfer rates. But if SCSI is carried over the network then the speed and performance could drop severely decline. Why iSCSI is recommended only for high-speed switched networks such as those that provide Gigabit Ethernet. Although iSCSI can run even on Fast Ethernet is not recommended if you seek performance, since disk access is slow down a lot.

The transfer speed of iSCSI is 1000 MB / Sec, but due to protocol, the low speed up to 800 MB / Sec. If we use cards DUAL CHANNEL, such as those with the QNAP, we get to 1600 MB / Sec taking into account losses by protocol.

ISCSI

The iSCSI protocol is an application layer protocol for transporting SCSI commands over a network. The thing to understand is that it is possible to export a device through a network by presenting it as a SCSI device. Besides the fact that the SCSI protocol is a standard industry massively deployed in production, is going through a conventional IP network reduces the cost of implementation compared to the deployment of storage solutions based on Fibre Channel. Furthermore, data backup can be done at the server level iSCSI, which limits the cost of the backup solution.

However, open source solutions are not numerous and it is difficult to convince an IT manager to switch to a solution of this type based on free software. For my part, I tried to use the OpenFile distribution based on rPath Linux (meta-distribution based on RedHat) and iSCSI Enterprise Target for Part iSCSI, but the product has not yet matured enough to consider professional use.

**spookshow** · 22-09-2010

ISCSI Server

Both the DataCore SANmelody Disk Server that FalconStor iSCSI Storage Server is the business unfamiliar networked storage. And their offer, to simplify, to mount an iSCSI SAN from scratch. Their aim is to provide the opportunity to centralize and consolidate storage resources or replicate data remotely, without investing in equipment SAN complex.

Their approach is very similar: to transform a Windows server (because it is more common in SMEs, according to publishers) in a storage platform with features of both NAS (file mode) and SAN (block mode), in their simply adding the necessary software layer. In fact, these two offerings are based on the success of their respective publishers, since they followed the main features SANmelody software SANsymphony while iSCSI Storage Server software uses some features of IPStor .

SANmelody Disk Server installed on a machine with Windows NT and requires the installation of an iSCSI client module. iSCSI Storage Server, meanwhile, fully integrated with Windows Storage Server 2003 with its package of services oriented storage such as VSS (Volume Shadow Copy Service). iSCSI Storage Server has been the ambition to add functionality to the SAN OS from Microsoft, historically oriented NAS (with Powered NAS).

ISCSI Windows

Unlike Windows Shares iSCSI data without a file system is available as raw data and how it works completely independent of a file system. That with even higher throughput, since the entire network overhead is eliminated on the network connection. iSCSI extended to some extent the SCSI hard drive cable through the TCP / IP network on TCP port 3260. iSCSI can be useful in additional disk space on VM servers, clients, or it also allows the diskless booting as terminal server clients over the network. Some applications such as MS Media Server only back on local disks and can thus secure iSCSI on network drives.

iSCSI Initiator

A client in an iSCSI storage network is called iSCSI Initiator Node (or short 'iSCSI Initiator'). This iSCSI initiator to connect to a server (iSCSI Target). The iSCSI initiator sends while SCSI commands to the iSCSI target. Those SCSI commands are packaged into IP packets to.

SCSI initiators are available in the following forms:

iSCSI hardware initiator: a PCI-X or PCIe card, the iSCSI Initiator functionality is implemented on. Such a map is called the iSCSI HBA. In a server operating system appears to be an iSCSI HBA, such as a RAID controller or a FC HBA. With an iSCSI HBA is possible to boot a server via iSCSI.
iSCSI Software Initiator: implemented in a software iSCSI initiator. The operators of the iSCSI initiator are carried out in this solution by the CPU of the server (and not from hardware components on a separate PCI-X/PCIe map). With the increased performance of current server-CPUs is now not a problem anymore. Hardware side are used here to communicate with the iSCSI Target ordinary network cards.

As long as booting from iSCSI is not a criterion, there is nothing against the use of iSCSI software initiators. With a little additional configuration initiator is a network boot using the iSCSI software even quite possible. Software iSCSI initiators are cheaper, very widespread and very stable. Also iSCSI over 10 Gigabit Ethernet is the future so easily with normal 10Gb Ethernet can be very implement themselves.

FreeNAS Server

The installation of a NAS server with FreeNAS software on a PC is very simple and easy to implement even for laymen. For 32bit systems LiveCD is the most current file 0.686.4 right. From the downloaded ISO image to burn with the CD burner of his choice a Boot CD which automatically takes over the entire installation. The FreeNAS software is very flexible and allows the construction of both a small NAS for playing and testing in-house network to a very large system with multiple disks in the RAID array for large server networks. If the NAS can be used professionally, it is advisable to use the NAS to install software on a bootable USB stick or a CF Flash card to IDE adapter.

Advantage is that one that separates the operating system from the NAS network panels and has not installed simultaneously on the network drive. If this fact must fail one, the NAS hard to reinstall. Not so when installed on a bootable USB stick or a CF / IDE adapter. Here you can turn all of the hardware, you just plug the USB stick or Flash adapter to a new machine and has a working immediately NAS actively with its individual configuration. The setup menu of the Boot CD offers all these options to menu-driven. Is that the NAS can also continue to install the CD Rom drive and the NAS again is the net. A SW update any of the FreeNAS NAS SW then settled comfortably in the future via the web interface as all other settings, too!

**spookshow** · 22-09-2010

Setting up the iSCSI target

Can FreeNAS is installed and booted it on the menu console IP address and LAN interfaces to its concerns (IP network, mask, set the gateway, etc.). Thereafter, the NAS is simply through a browser with IE / Firefox etc. configurable with http:// <abc.nas.ip> You can go easily there.

The default password to login is: User: admin, Password: FreeNAS . Initial tests with simple Windows shares (under Services CIFS / SMB), and as FTP Server you can now do if the NAS is to provide these services in addition to iSCSI on the network. Advance a few general remarks on the establishment of an iSCSI target. There are two ways to set up an iSCSI Target.

In Device (disk), the basic
On a file basis

iSCSI shares are currently pure point to point applications is not possible to get shared by several users. For servers, disk space is usually takes all the disks or RAID array to the space on redundant disk systems to outsource the network.

If you have several small software or service will use the iSCSI disk on a NAS with Windows shares (Shares) and / or the FTP or TFTP service, then come be a file-based iSCSI target for use as a Disk Device with FreeNAS currently can only be released as a block device and a sharing with an example, Windows SharePoint is not possible.

First of all you have to create a 3GiGs large file as a container file.
This one uses the shell to access the console or unlock the service menu of the web interface, SSH access.
SSH you can then use the program date Putty or TeraTerm connect to the NAS and with root privileges (user: root: FreeNAS] login password.
You put a directory with mkdir e.g. iSCSI, or does this through the Windows Share access which you must activate before.
After that change with iSCSI cd to that directory and created with here:
dd if = / dev / zero of = bs = 1k count = image1.img 3M
3Gigs a container file. (Please take a little patience to create)
3M stands for 3gigs, this value is variable and can of course be changed according to individual requirements!
Back in the web interface, you go in FreeNAS Setup menu, then under Services > iSCSI Target
Then to back with Save and restart the iSCSI target and is now active on the FreeNAS

Set up your Windows XP or Vista client

For the connection initiator is the Microsoft "iSCSI" requires that one Vista from the Start menu search box found at. Windows XP has by default it does not have on board, but below that offered by Microsoft for Windows XP for free download from the official site.
Following installation of the SW, restart the iSCSI initiator and claims, discovery, and add local IP address of the FreeNAS only one.
After that change to the menu it automatically targets and needs of the FreeNAS iSCSI target <….> netbsd.iscsi-target: target0 see the status with the NOT connected or inactive.
Here you click on the button now Log On
Selects the target (gray) and then just OK.
You should now see the status in the menu Target automatically "Connected" switch on!
So now is the successful connection to the iSCSI disk is in the network and use nothing stands in the way
It is now only one file system under Windows to set up what simple and banal, as in conventional hard drives, via the Windows Control Panel, and then > Administration > Computer Management > Disk Management.
Disk Manager now automatically remembers that there is a new disc is offering the formatting automatically. Otherwise, does this one right on the new disk. It is now formatted as an NTFS volume, and has a logical drive such as I (like iSCSI).

Disk storage via iSCSI

The iSCSI protocol connects PCs with network hard drive, so how they can use locally installed devices. So you can even operate without a PC hard drive built: the open-source boot loader gPXE start a PC directly from an iSCSI drive - such as low-noise media center in the living room. The network protocol called iSCSI builds data center storage area networks ( SAN ), server systems as required to supply the hard disk. The wiring of memory networks with conventional Gigabit Ethernet via TCP / IP and iSCSI is much cheaper than specialized Fibre Channel connections, which are designed for high transfer performance and redundancy.

Meanwhile, can the desktop operating systems and some iSCSI NAS devices upmarket as iSCSI Target to free space. And Linux systems are iSCSI-ready releases, such as the NAS distributions FreeNAS and Openfiler. Unlike traditional network shares, of which some users with the Microsoft SMB files can retrieve protocol, iSCSI always transmits raw data blocks over the line and works independently of a file system. This saves network overhead , and promises high data throughput. Via iSCSI extended to quasi one hard drive cable through the local network to make it directly to a client PC. The data runs via a simple TCP connection, the server listens by default on port 3260.

Once you connect with a Windows iSCSI share, in the Disk Manager appears an additional hard drive, which is indistinguishable at first glance from a local physical. You can partition and format as usual with a file system. In small offices and home networks, the iSCSI protocol to be useful to give certain applications more space, do not work easily with a conventional network share. Sun distinguishes Microsoft's Media Center TV programs can usually only on local hard drives - via iSCSI to use for a network hard drive.

iSCSI shares are only suitable for point-to-point connections: The protocol does not know any safe mechanisms to multiple users simultaneously access the same network storage. iSCSI offers a ( CHAP ), encrypts the transmitted data itself but not sure who wants the local network, no one iSCSI data on line can read along in the need to connect with IPSec encryption.

Microsoft provides an iSCSI target with only the specialized Windows Storage Server, Windows Server 2003 and 2008 from house no free space via iSCSI. If you are a Linux iSCSI Target not make friends with like, is this the free version of StarWind software that is also a Windows XP-based PC can share via iSCSI storage.

There is already a handful of NAS devices that function as an iSCSI target, and the cheap models to know the protocol is usually not. The iSCSI implementation, it also seems to be differences from one NAS device, Thecus company wanted a Windows XP, which we had prepared as described in the following for the network boot does not boot.

**spookshow** · 22-09-2010

Linux ISCSI

On a Debian Linux-related system such as Ubuntu, the iSCSI server can be conveniently re-install with the package management: sudo apt-get install iscsitarget
The configuration file / etc / ietd.conf defines the shares. In the simplest case, ensure sufficient two lines: Target iqn.2009-02.local: ctsan Lun 0 Path = / dev/sda3, Type = fileio

These details make the iSCSI share at the behind Target specified "iSCSI qualified name (IQN known). The cryptic iqn string starts with "." Followed by a year and a month first, followed up with a domain name. In a small system, you can choose the domain name at will. The indication of the year and the month is provided in the iSCSI standard, because domain names expire and change hands can. After the colon you need to decide an arbitrary identifier.

The second line the shared storage device in case it is the whole partition / dev/sda3. The Linux software accepts this arbitrary block devices, LVM volumes, and even image files. An empty 4GB large image created one instance with the dd command.

On Windows, you can now try to integrate the newly defined iSCSI drive. Apply the required iSCSI initiator is Vista's Start menu search box. For Windows XP, Microsoft provides the initiator with an identical interface to download to. On the tab search to make a new "portal" with the IP address of the Linux server to add.

Should appear immediately on the objectives of the previously created iSCSI shares that can be integrated with a mouse click on Register. In Disk Management, then we get a new hard drive. If the iSCSI storage is empty, beats Windows in such a factory plate, they initialize with a master boot record or as a GPT disk, so they are then partition and format can be.

Network boot

With the open-source project Etherboot developed the boot loader to boot the Windows operating systems and Linux from an iSCSI share. Thus, a client PC can be whisper quiet with no internal hard drive running around the living room that brings all the information from the local network and there bears. The conventional technique PXE network boot requires a more complex infrastructure and can neither afford nor XP Vista start. Only the mini-Windows PE (Preinstallation Environment; see emergency Windows 2009 ) can PXE boot via.

Our attempts to a Windows PC without a local hard disk to run gPXE with were successful: between two via Gigabit Ethernet wired standard PCs, we measured on Windows XP using the Disk Benchmark h2benchw a throughput of almost 48 MByte / s - faster than many a notebook hard drive.

Go on an iSCSI-sharing cannot install XP or Vista, so it must first prepare an installation and play them as an image on the server. Our attempts to set up a test system under VMware and the copied image of it to boot via iSCSI were fruitless - for the first steps, it is important to install the Windows system on the identical hardware that will later boot over the network. In particular, the same network card must be installed on the PC loads its operating system later.

To prepare Windows XP to boot via iSCSI, to install a special bootable version of Microsoft's iSCSI initiator. The conventional initiator missing some necessary files for booting. In the etherboot it is in addition to the XP SAN Boot Configuration is available. The included batch script setup.bat installs another driver and is the network driver in the boot order to the front, so remove them at startup early enough on.

For Windows Vista, these preparations are not necessary, and the bootable iSCSI Initiator is already on board and additional driver does not need. In our experiments, Vista has started smoothly, but only via iSCSI, if the source system was installed in the network already.

Troubleshooting

Before the start via iSCSI finally worked, we have made some futile attempts. Doubt whether the loader gPXE the iSCSI target at all appealing, you can remove the network sniffer Wireshark, which also analyzes the iSCSI protocol. When Windows starts to boot from the release, but then breaks off, the problem is probably to look at the configuration of the network and the iSCSI driver. Start the process with the boot.ini parameter /bootlog can log worked on our test system - probably because the Windows iSCSI storage from the first gPXE loader provided BIOS functions could talk about only with the native drivers, but failed.

The developers describe the etherboot wiki yet another method , the boats on the fingers to look to Windows, the correct boot parameters start with, the serial port, Windows interesting debugging information about the Microsoft Debugger Windbg on another PC can evaluate. We hardened the suspicion that our test Windows, the iSCSI share at crucial time could incorporate as a boot device.

In many cases, it would virtually ensure that installed on a Windows iSCSI Target turns to run on different PCs - but Windows is rather squeamish when it when starting a completely different hardware finds. In the etherboot wiki explain the developer how about additional Windows kernel and HAL files in the XP boot menu integrates to the start to choose the right hardware for the system files. You will also find detailed instructions on how to the iSCSI Windows with the network of another known target PC.

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