RAID

RAID Overview

Data redundancy and speed are important considerations for any network attached storage system. Most NAS systems use multiple disks to store data, meaning you should decide what type of RAIDto use before installing FreeNAS®. This section provides an overview of RAID types to assist you in deciding which type best suits your requirements.

RAID 0 (stripe): provides optimal performance and allows you to add disks as needed. Provides zero redundancy, meaning if one disk fails, all of the data on all of the disks is lost. The more disks in the RAID 0, the more likely the chance of a failure.

RAID 1 (mirror): provides redundancy as data is copied (mirrored) to two or more drives. Provides good read performance but may have slower write performance, depending upon how the mirrors are setup and the number of ZILs and L2ARCs.

RAID 5: requires a minimum of 3 disks and can tolerate the loss of one disk without losing data. Disk reads are fast but write speed can be reduced by as much as 50%. If a disk fails, it is marked as degraded but the system will continue to operate until the drive is replaced and the RAID is rebuilt. However, should another disk fail before the RAID is rebuilt, all data will be lost. If your FreeNAS® system will be used for steady writes, RAID 5 is a poor choice due to the slow write speed.

RAID 6: requires a minimum of 4 disks and can tolerate the loss of 2 disks without losing data. Benefits from having many disks as performance, fault tolerance, and cost efficiency are all improved relatively with more disks. The larger the failed drive, the longer it takes to rebuild the array. Reads are very fast but writes are slower than a RAID 5.

RAID 10: requires a minimum of 4 disks and number of disks is always even as this type of RAID mirrors striped sets. This type of RAID can survive the failure of any one drive. If you lose a second drive from the same mirrored set, you will lose the array. However, if you lose a second drive from a different mirrored set, the array will continue to operate in a degraded state. RAID 10 significantly outperforms RAIDZ2, especially on writes.

RAID 60: requires a minimum of 8 disks. Combines RAID 0 striping with the distributed double parity of RAID 6 by striping 2 4-disk RAID 6 arrays. RAID 60 rebuild times are half that of RAID 6.

RAIDZ1: ZFS software solution that is equivalent to RAID5. Its advantage over RAID 5 is that it avoids the write-hole and doesn't require any special hardware, meaning it can be used on commodity disks. If your FreeNAS® system will be used for steady writes, RAIDZ is a poor choice due to the slow write speed.

RAIDZ2: double-parity ZFS software solution that is similar to RAID-6. It avoids the write-hole and doesn't require any special hardware, meaning it can be used on commodity disks. RAIDZ2 allows you to lose 1 drive without any degradation as it basically becomes a RAIDZ1 until you replace the failed drive and restripe. At this time, RAIDZ2 on FreeBSD is slower than RAIDZ1.

RAIDZ3: triple-parity ZFS software solution. RAIDZ3 offers three parity drives and can operate in degraded mode if up to three drives fail with no restrictions on which drives can fail.

Core Concept

What is core-------A standard processor has one core (Single-core). Single core processor only process one instruction at a time (They do use pipeline internally, which allow several instructions to be processed together, however they are still run one at a time.

What is a multi-Core Processor--------A multi-core processor is composed of two or more independent cores, each capable of processing individual instructions. A dual-core processor contain tow cores, a quad-core processor contains four cores, and a hexa-core processor contains six cores.

Why do I Need Multiple Cores?

Multiple cores can be used to run two programs side by side and, when an intensive program is running, (AV Scan, Video conversion, CD ripping etc.) you can utilize another core to run your browser to check your email etc.

Multiple cores really shine when you’re using a program that can utilize more than one core (called Parallelization) to improve the program’s efficiency. Programs such as graphic software, games etc. can run multiple instructions at the same time and deliver faster, smoother results.

So if you use CPU-intensive software, multiple cores will likely provide a better experience when using your PC. If you use your PC to check emails and watch the occasional video, you really don’t need a multi-core processo

How many cores do i3, i5, and i7′s have?

• A Dual-core processor has two cores
• A Quad-core processor has four cores
• An i3 processor has two cores
• An i5 processor has two or four cores (depending on the model you have)
• An i7 processor has two, four, or six cores (depending on the model you have)

How Do Core 2 Duo and Core 2 Quad Compare with Core i3, i5, and i7?

If you’re looking for a good value PC and have decided on a Core 2 Duo, Core i3, or Core i5 (all best in value for casual computer use).
Core 2 Duo processors run two threads; i3′s and i5′s run four threads. Core 2 Duo processors are socket 775 (45/65nm); Core i3 and i5 processors are socket 1156 (nm) but only work with DDR3 RAM (Some Core 2 Duo’s work with both DDR2 and DDR3.)
For desktops, I’d stay clear of core 2 duos due to their lack of power; for laptops, it all depends on your usage. As laptops aren’t as easy to upgrade, buying dated technology might burn you in the future when you find your Core 2 Duo PC’s motherboard only supports 4GB RAM–for example.
i5′s come with “turbo boost”; however, i3′s overclock very well if that’s your thing. That’s where I’d put my money if you’re considering Core 2 Duo, i3, and i5: the i3 provides the best value for most casual PC users.
While I focused on i3, i5, and Core 2 Duo to answer a reader’s question, the principles apply when comparing i5, i7, and Core 2 Quad. I’d go for the i5 unless you are willing to pay a premium for a little more performance.

Intel Hyper-Threading Techonlogy

Depending on when you last bought a computer, you may remember Hyper-Threading as a feature that Intel introduced and then discontinued. This could understandably leave a sour taste in your mouth – why would Intel discontinue it if it wasn’t trouble?
The truth isn’t so grim. Hyper-Threading was for a time made available on certain Intel Pentium 4 and Intel Xeon processors. It was discontinued not because the feature itself was bad, but rather because the processor that used it turned out to be a bit of a misstep for other reasons. The Pentium 4 architecture was a minor disaster for Intel because it was incapable of going the direction Intel hoped (Intel wanted to have Pentium 4 processors with clock speeds of up to 10 GHz). As a result, Intel jumped back to designing processors based on the Pentium Pro family tree.

 Alright, enough with the technical mumbo-jumbo. Now let’s get down to the most important part – how Hyper-Threading will impact the performance of the computer are thinking of building or buying.
In terms of day-to-day tasks like web browsing, email and word processing, Hyper-Threading won’t have much of an impact. Yes, Hyper-Threading is theoritically better at multi-tasking. However, today’s processors are so fast that basic programs are rarely limited by the speed of your processor. The way programs are coded can also be a limitation. You may sometimes find that you have numerous programs open, but only one of your processor cores is being put to much use. That’s because the programs are, for whatever reason, not having their work divided among the different cores available.
When you’re trying to do some heavy lifting, however, Hyper-Threading can be more helpful. The applications most likely to benefit are 3D rendering programs, heavy-duty audio/video transcoding apps, and scientific applications built for maximum multi-threaded performance. But you may also enjoy a performance boost when encoding audio files in iTunes, playing 3D games and zipping/unzipping folders. The boost in performance can be up to 30%, although there will also be situations where Hyper-Threading provides no boost at all.

The FreeNAS™ Project

Storage for Open Source

FreeNAS™ is an Open Source Storage Platform based on FreeBSD and supports sharing across Windows, Apple, and UNIX-like systems.  FreeNAS™ 8 includes ZFS, which supports high storage capacities and integrates file systems and volume management into a single piece of software.

We can download free nas software from here.
http://sourceforge.net/projects/freenas/files/FreeNAS-8.0.4/

We need not to buy a storage device. We can make a local system to nas device.

DYI Small Business Storage: Build Your Own NAS Device

If you've ever considered purchasing a NAS (short for network-attached storage) device to add storage to your home or small office network, you may have balked due to the relatively high prices they can command. If you don't have hundreds of dollars to spare on a commercial NAS product, but you do have an old or unused PC lying around, you might consider pressing it into service as a NAS device.

If you have the time and are comfortable with basic network technology, one way to convert that spare PC into a NAS server is with a free utility called FreeNAS. Like many commercial NAS products, FreeNAS is built atop FreeBSD (a compact Unix-basedoperating system). FreeNAS offers pretty much all the features common in a ready-made NAS device and then some, but best of all, it can run on pretty modest hardware — the main requirements are a system with a minimum of 96 MB of RAM, a bootable CD/DVD drive, and, of course, at least one hard drive (external USB drives are also supported).

There are a few versions of FreeNAS available, but here we'll focus on the basic setup of the LiveCD version. The nice thing about this version is that you don't need to permanently install it onto your system. Instead, you can boot FreeNAS directly off of a CD or DVD — it will run from a RAM drive (using only around 32 MB of memory) and can save its configuration data to either a USB Flash drive or even an old-school floppy disk.

To get FreeNAS, download the most recent version listed under FreeNAS ISO (as of this writing, it was version 0.686b2, dated 11-18-2007). After you've downloaded the approximately 44 MB file, you'll need to create a bootable CD from the ISO image file (as opposed to simply burning the file to a disc). Windows built-in burning tools won't do this for you, but pretty much any commercial burning software such as Nero Burning ROM or Roxio Easy Media Creator will. (If you need it, ISO Recorder is a free utility that works with XP and Vista — you'll find it here.

Before loading FreeNAS, make sure your system's set to boot directly from its CD or DVD drive. You can do that from the system BIOS, which you can access by pressing a key when prompted — usually F2 or Del — right after powering up the system. The exact menu options will vary slightly by system or BIOS vendor, but you're looking for settings that refer to boot order; when you find them, make sure that CD/DVD or optical drive is listed as the first boot device. (If you have any external drives you want to use with your FreeNAS system, you can either connect them now or wait until later.)

Installation and Network Configuration

After you've configured the system's boot order, insert a blank formatted floppy disk (or connect a Flash drive), insert the FreeNAS CD and then reboot your system. FreeNAS will start loading and eventually display a boot menu on a 5-second timer. Leave the default option selected, and within a few seconds asplash page will appear. After a few more moments there will be high-pitched beep, which means FreeNAS is loaded and ready to configure.

After you hear that beep, press ESC to gain access to the Console setup menu. Select option 2, Set LAN IPaddress, and you'll be prompted about using DHCP for IPv4 and then AutoConfiguration for IPv6. Choose Yin both cases, and after a moment FreeNAS will display the addresses that have been assigned for each. The IPv6 address isn't really important, unless you're running IPv6, but take note of the address listed for IPv4 — this is the address you'll use to access and configure your FreeNAS system.

You can test FreeNAS's network connectivity by returning to the setup menu and then selecting option 5,Ping host. Enter the address of your router, and if you get responses, you'll know your NAS system's link is up. If so, point your browser to the FreeNAS system's IP address, enter admin as the username and freenas as the password, and you'll be granted access to the configuration screen.

Preparing Disks and Creating Shares

There are three basic steps to preparing a disk for use with FreeNAS: identifying it, formatting it and mounting it. Start by going to the Disks menu, selecting Management, and clicking the plus sign button. From the Disk pull-down menu — which will list all disks connected to the system) select one that you want to use, click the Add button and then click Apply changes.

Now go to Disks|Format, select the disk you just added, and click the Format Disk button. (As you'll be warned, this will erase the contents of the disk.) Then go to Disks|Mount Point, click the plus button, specify the drive, type a volume name into the Name field, then click Add. Again, Finally, click the Add Changes when it appears.

Now we need to activate file services and set up a share. Head over to the Services menu and chooseCIFS/SMB (this is the protocol used by Windows Networking, a.k.a. Network Neighborhood/Places). Put a check in the Enable box in the upper right and give your server a name in the NetBIOSName field. (You can also change the Workgroup name from the default of WORKGROUP if you use something else.)

Click the Save and Restart button, and then return to the top of the page and click the Shares tab. To create a share, click the plus button, enter a share name and description into the Name and Comment fields, respectively, then point to your newly created volume in the Path field (you can use the ellipse button to browse for it). Click Add and then Apply changes, and you're done. You can make sure your FreeNAS share is visible from an Windows system by or browsing for it within Network Places. (If your system has a software firewall and you can't reach the FreeNAS system, you may need to configure it to allow Windows File and Printer Sharing.)

Wait, There's More

We've only covered a basic configuration of FreeNAS here, but there's a lot more you can do with it. For starters, you can use it to share out multiple drives, including CD or DVDs. Like most commercial NAS products, FreeNAS will let you set up user accounts and rights, or you can have it authenticate users from an existing Windows domain (2000/2003 Active Directory only). You can also enable other network services including UPnP, FTP, NFS (for Linux), or AFP (for older Macs) and set up encrypted volumes or one using (software-based) RAID 0, 1, or 5. For more information on these and other FreeNAS features consult the product manual, which is surprisingly useful (it's available in PDF format from the download page).

Using FreeNAS to build your own NAS server won't necessarily make sense for everyone. As you can see, it requires a bit more configuration effort than a commercial NAS product, so you have to have the time and inclination to play with it and tweak it to your needs. It's also worth nothing that since a PCs is usually much larger than a typical NAS device, it may be harder to tuck a FreeNAS system away somewhere if space is tight. Also, that any PC-based NAS is likely to be nosier and consume more power than than a ready-made NAS (worth keeping in mind considering your NAS device will probably need to run 24/7).

But if you've got more time, space, and equipment than you do cash, FreeNAS is an excellent way to set up effective and inexpensive network storage.

Joe Moran spent six years as an editor and analyst with Ziff-Davis Publishing and several more as a freelance product reviewer. He's also worked in technology public relations and as a corporate IT manager, and he's currently principal of Neighborhood Techs, a technology service firm in Naples, Fla. He holds several industry certifications, including Microsoft Certified Systems Engineer (MCSE) and Cisco Certified Network Associate (CCNA).