Important: There are many different implementations of RAID. Among the most common are RAID 0, RAID 1, and RAID 5.

RAID 0 uses striping to create a single large-capacity drive with high throughput. RAID 0 is much faster and more efficient than using two separate drives. However, a major disadvantage is that the stripes are not redundant; if one of the drives fails, all of the data will be lost. Therefore, RAID 0 should not be used as "data backup insurance." RAID 0 is all performance and no protection.

RAID 1 is redundant but not striped. The same data is stored on two (or more) different drives. RAID 1 is also called disk mirroring. The data is protected, but performance is much slower with RAID 1.

RAID 5 uses three or more drives (usually between three and five). RAID 5’s redundancy is based not on mirroring but on parity. Parity is a computational method in binary logic that generates a parity value from a set of data. If any one of those data elements is lost, it can be recreated using the remaining data and the parity value, no matter which element is lost. In RAID 5, this means that parity can completely reconstruct one of the drives in the array in the event of a failure.

Notes:

• For support for Samsung hard disk drives set in a RAID array, see the documentation for your PC’s motherboard or your host controller card.
• If you don’t know what motherboard or Serial ATA controller you are using, see the instruction or owners manual for your computer. You can also contact your computer manufacture for support. Not all manufactures are listed here, the tables below offer a list of the most common manufactures. If your manufacture is not listed here perform a Google search for their support site.

RAID 1 Explained
The RAID level 1 architecture uses the concept of mirroring. This means that errors and failures of all disks can be accommodated in the disk array, except one. However, there can be maximum two disks only. RAID 1 is designed for faster read operations than write. RAID 1 recovery is only possible when one of the two disks have failed. While using any modern multi-threaded operating system (Windows or Linux), RAID 1 array gives better performance for split seeks, that is, access of same memory location by two different users. There needs to be a RAID 1 controller for each disk in this array for best performance.

RAID 5 Explained
In the architecture of RAID 5 disks, the array is so arranged that failure of one disk can be kept hidden. If the second disk fails before the replacement of the first, then there cannot be any data recovery. The maximum number of disks that can be accommodated in the architecture are three, out of which one is kept as a backup. When the first disk fails, the backup disk springs into action and data recovery is possible. In RAID 5, a failed disk needs to be replaced as early as possible. RAID 5 performance suffers whenever there is a read-modify-write operation.

Recovery in RAID Disks
RAID 5 as well as RAID 1 have one common assumption. Every failure is independent of the other. However, this is not completely true. Due to the mechanical nature of the storage disk, failure of one disk may mechanically be dependent on the other. There are techniques such as, parity resynchronization or stale sub-disk recovery, where recovery is possible but these are restricted to specific scenarios. Data loss due to software reasons (a virus or accidental deletion) is however a different issue. The data recovery techniques used in RAID disks and recovery through data recovery softwares are not directly related.

Advantages of RAID 1

• Redundancy of the data is hundred percent.
• Data need not be rebuilt in case of a single disk failure.
• Even though there are two disks in the array, the rate at which data gets transferred is that of a single disk.
• Very easy to understand and implement.

Advantages of RAID 5

• RAID 5 has an inbuilt load balancing mechanism.
• RAID 5 is ideally suited for database applications which are heavily read oriented.
• Applications that perform random read operations work well on RAID 5.
• High fault tolerance typically requires additional disk space. RAID 5 is highly efficient in that scenario.

The seven levels in RAID have been developed gradually over a period of time. Different arrays are suited for different situations. The above RAID 5 vs RAID 1 comparison may be helpful in understanding these disk array structures.

If you install and use a desktop edition hard drive connected to a RAID controller, the drive may not work correctly unless jointly qualified by an enterprise OEM. This is caused by the normal error recovery procedure that a desktop edition hard drive uses.

When an error is found on a desktop edition hard drive, the drive will enter into a deep recovery cycle to attempt to repair the error, recover the data from the problematic area, and then reallocate a dedicated area to replace the problematic area. This process can take up to 2 minutes depending on the severity of the issue. Most RAID controllers allow a very short amount of time for a hard drive to recover from an error. If a hard drive takes too long to complete this process, the drive will be dropped from the RAID array. Most RAID controllers allow from 7 to 15 seconds for error recovery before dropping a hard drive from an array. Western Digital does not recommend installing desktop edition hard drives in an enterprise environment (on a RAID controller).

Western Digital RAID edition hard drives have a feature called TLER (Time Limited Error Recovery) which stops the hard drive from entering into a deep recovery cycle. The hard drive will only spend 7 seconds to attempt to recover. This means that the hard drive will not be dropped from a RAID array. Though TLER is designed for RAID environments, it is fully compatible and will not be detrimental when used in non-RAID environments.

RAID is an acronym for Redundant Array of independent Disks. With RAID enabled on a storage system you can connect two or more drives in the system so that they act like one big fast drive or set them up so that one drive in the system is used to automatically and instantaneously duplicate (or mirror) your data for real-time backup.

There are three reasons you might want a RAID system of drives.

1. You need tons of storage space and you need it to be fast. (RAID 0)
2. You want to instantaneously and automatically backup your data. (RAID 1)
3. You want both. (RAID 5)

Which RAID mode should i use?

1. Speed (RAID 0)

Set in high-performance mode (also called striped mode or RAID 0) the storage system gives you the power you need when you’re:

• Designing huge graphics and need a lightning-fast photoshop scratch space.
• Recording large DV files while maintaining clean audio performance.
• Editing DV or HD video and want a smooth work flow with no dropped frames.
• Rendering complex 3D objects or special effects.
• performing disk-intensive database operations.
• Driven to be the first geek on your block with a computer so fast it blows your socks off.

Why is RAID 0 so fast? it’s a bit complicated, but suffice it to say that two or more heads, or in this case, drives, are better than one. picture multiple hoses filling a bucket at the same time or several men bailing a boat and you can understand why two drives striped are faster than one. Data is saved (striped) across both drives and accessed in parallel by all the drives so you get higher data transfer rates on large data accesses and higher input/output rates on small data accesses.

2. Data protection (RAID 1)

Set the system to data protection mode (also known as mirrored mode or RAID 1) and the capacity is divided in half. Half of the capacity is used to store your data and half is used for a duplicate copy.

Why do i want that kind of redundancy? it’s your data, your family pictures, your movie of baby’s first steps, your first novel. is it important? You decide. if it is, then RAID mirroring is for you.

3. Data protection and speed (RAID 5)

in systems with three or more drives (like 4 TB WD ShareSpace™ Network Storage System) we recommend that you set the system to RAID 5. This gives you the best of both worlds: fast performance by striping data across all drives; data protection by dedicating a quarter of each drive to fault tolerance leaving three quarters of the system capacity available for data storage.

About Spanning (Linear)

Spanning, which is not a RAID mode, combines all the drives in a system into one big volume so they act like one giant drive.  The drives are filled up one drive at a time.  The advantage of using this mode is that you can add more drives without having to reformat the system.

The name BlackArmor was first introduced in 2008 as a portable Full Disc Encryption drive, however, at that time it was termed the Maxtor BlackArmor.  Now we are extending the use of that product name under the Seagate brand. Seagate BlackArmor is now the family name for a suite of storage solutions packaged for small business.  The Seagate BlackArmor NAS 440 and Seagate BlackArmor NAS 420 network storage servers are just the first two solutions in what will be a complete lineup of BlackArmor products, to include 4 Bay, 2 drive and 1 drive NAS products, Desktop direct attach products and portable products

What are the System Requirements for the BlackArmor NAS 440?

PC On Network

• Pentium III, 500MHz equivalent processor or higher
• Microsoft® Windows® XP or Windows Vista® operating system
  (32-bit & 64-bit support)
• Internet Explorer 6.0 or later, or Firefox 2.X or later
• 256MB RAM or Higher
• CD/DVD-ROM for software installation and system recovery

Mac On Network

• Mac OS X 10.4.11 or later
  (both PPC & Intel-Based Macs supported)
• Apple Safari 3.1 or later
• CD/DVD-ROM for software installation

What is the Warranty Period for the Seagate BlackArmor NAS 440?

The Seagate BlackArmor NAS 440 comes with a 3-Year Limited Warranty.

How much does a Seagate BlackArmor NAS 440 cost?

Seagate BlackArmor NAS 440 and BlackArmor NAS 420 will be available for purchase through channel partners and select retailers at a manufacturers’ suggested retail prices (MSRP) of $799.99 USD for 2TB; $1,199.99 USD for 4TB; $1,699.99 USD for 6TB and $1,999.99 USD for 8TB (expected availability scheduled for May).

What capacities are available with the BlackArmor NAS 440?

The Seagate BlackArmor NAS 440 comes in the following sizes:

• 2TB (NAS 420 ONLY)
• 4TB
• 6TB
• 8TB

What is the Seagate BlackArmor NAS 420?

The 420 is essentially the BlackArmor NAS 440 with these differing characteristics:

• Ships with only two (2) hard drives; the other two hard drive bays are empty.
• The default RAID configuration of a 420 is RAID 1, not RAID 5 like its 440 counterpart

Note: Although you will rarely see reference to Seagate BlackArmor 420, all FAQs found here refer to both Seagate BlackArmor NAS 440 and Seagate BlackArmor NAS 420 products together unless otherwise noted.

How many Users can the Seagate BlackArmor support?

The Seagate BlackArmor servers are targeted to the SMB/SOHO customer and are designed to support up to 50 clients.

What is Seagate BlackArmor Backup and what can it actually back up?

Seagate BlackArmor Backup is a comprehensive Backup Utility made by Acronis and skinned for use with the Seagate Black Armor Family. BlackArmor Backup can perform Full-System, Incremental and Custom backup

How many Seagate BlackArmor Backup client licenses are provided with the Seagate BlackArmor NAS 440?

BlackArmor ships with 10 licenses out-of-the-box, however, additional licenses can be purchased in 2 and 5 -set increments on the Seagate Website.

Can I perform a Full System Backup and/or Restore with the Seagate BlackArmor Backup software?

Yes you can use BlackArmor Backup software to perform Full System Backup of your Windows XP and/or Vista computer.
You can also recover from system problems via the use of BlackArmor Recovery software included on the CD. With this CD, you can boot up your system, access the BlackArmor and Restore from a complete system backup.

Can I use Time Machine to Back Up my Mac to the Seagate BlackArmor NAS 440?

Apple does not support the use of Time Machine with networked drives, with the exception of its own Time Capsule.

What is the difference between Port Aggregation and Port Replication?

The server’s two LAN ports can be configured for link aggregation, which means you can connect both LAN ports to your network at the same time and improve transfer performance. Your BlackArmor server then uses both network connections simultaneously so that it can transfer data at a faster rate.

Note: The speed of your network connection doesn’t change. With link aggregation, your BlackArmor server sends and receives information through both LAN ports at the same time, which increases “throughput”. Link aggregation is not unlike using two hoses to fill a bucket instead of one—using two hoses doesn’t make the water flow any faster, but the bucket fills more quickly.

Alternatively, you can use one LAN port to connect to your network and the other LAN port to set up replication, or archive backup, where an exact copy of the data on your BlackArmor server is created and maintained on a second BlackArmor server.

Can I access the BlackArmor NAS 440 from PCs that are already part of a workgroup or domain?

Yes – by default, the Seagate BlackArmor NAS 440 is configured to join the WORKGROUP Workgroup. However, with a couple of setting changes and Domain Admin authentication, the NAS 440 can become part of a Domain. It is important to point out that other factors need to be addressed before this product can effectively participate in Active Directory. Contact your System/Domain Admin if you require assistance.

Is the Seagate BlackArmor NAS 440 compatible with Linux?

Yes and No. The Seagate BlackArmor NAS 440’s Web UI can enable NFS access to shares when created or modified. These shares can then be mounted using various Linux GUI (e.g., KDE or Gnome) and/or Command-Line usage. Refer to your Linux documentation for more information.

What Protocols are supported?

The following Network Protocols are supported:

• HTTP

• HTTPS

• CIFS

• FTP

• NFS

• Bonjour

• Microsoft Rally

How do I know if my printer will work when connected to the Seagate BlackArmor NAS 440?

The Seagate BlackArmor provides support for USB Printers when properly configured. Windows Users should configure a Network Printer and Mac Users should do the same or trying connecting through a Windows printer if one is configured for Windows Users.

Note: USB, All-In-One (AIO) Printers are not supported

What Levels of RAID are available with the Seagate BlackArmor NAS 440?

By default, the Seagate BlackArmor NAS 440 comes with a pre-configured RAID 5 Volume. The Seagate BlackArmor 420 comes with a pre-configured RAID 1 Volume. However, both can be set with user-configurable RAID 0/1/5/10 & JBOD volumes. By default the NAS 420 can be configured as RAID 0 or 1. The other RAID schemes become available when two (2) more drives are added to the unit.

Are the hard drives in the Seagate BlackArmor NAS 440 hot – swappable?

In the event of a Drive Failure, users can run the BlackArmor in a degraded state and replace the defective drive with a good drive. After which, you can rebuild the RAID volume using the BlackArmor Manager’s Web UI.

Note: Never remove more than one (1) drive from the BlackArmor at any given time while power is on. Failure to do this may result in data loss.

What other replacement parts are available for the Seagate BlackArmor NAS 440?

Along with Hard Drives, you can also replace the following accessories:

• Cooling Fan
• Hard Drive Tray/Sled
• Power Supply

How can I remotely access the Seagate BlackArmor NAS 440?

Users can remotely access and share content with others via Seagate Global Access. Users can also opt to provide remote access through Dynamic DNS as well.

Can I share my music, movies and photos with media streaming devices?

Yes. The BlackArmor NAS 440 is both iTunes Server and a DLNA Compliant Digital Media Server. This means that not only can you store digital content on your BlackArmor NAS 440; you can also stream it to systems using iTunes and other DLNA Media Adapters.

Where can I find more information and/or help for the Seagate BlackArmor NAS 440?

For more information about your BlackArmor server, see:

• BlackArmor Quick Start Guide (printed)
• BlackArmor Manager Help
• BlackArmor Discovery Help
• BlackArmor Backup User Guide
• BlackArmor Backup Help
• Readme file

For more information, please refer to the Seagate Web site at www.seagate.com.

Highlights

• User-configurable RAID solution
• Use RAID 0 for high performance disk striping or RAID 1 for automatic mirroring
• Up to 1 TB storage capacity
• FireWire® 800 for fast data transfer
• Oxford 924 chipset
• Pre-formatted for Mac; easily formatted for Windows®
• Available in RAID 0 only, and RAID 0 / RAID 1 (user configurable) configurations.

What does this mean?

Maxtor OneTouch III Turbo drives are shipped with 2 drives inside the enclosure. These drives are configured in such a way that the drive letter or volume spans both drives to make one large drive. This is known as RAID 0 or RAID Striping.

When data is written to this large volume, the data is "striped" across the two drives.  The stripe size is 64 KB. What this means is that a file written to the array is split into two parts, one for each drive. This translates into significant improvement in reads and writes because two drives can do the work of one in roughtly half the time. This usually means throughput of 30-40% higher than a single drive, and sometimes can be nearly 50% higher.

The file splitting is automatically handled by the operating system so it makes it a simple and robust solution for adding speedy storage or backup.

RAID is an acronym which stands for "Redundant Array of Independent (or Inexpensive) Disks" which is not entirely accurate for the way RAID 0 is used because there is no redundancy. A RAID 0 volume needs to be backed up but is extremely fast.

The following illustration shows how data is arranged on the two drives in RAID 0 and RAID 1:

RAID 0
Pros:

• 1 file is stored on both drives.
• Significantly improved throughput because two drives are being accessed to read or write the same file.
• Large capacity volume.

Cons:

• RAID 0 is not redundant. Files need to be backed up in case of drive failure.

Note:  Stripe size = 64 KB.

RAID 1

Pros:

• 1 full file is written to both drives simultaneously.
• One drive is a mirrored copy of the other in case of drive failure, automatically.

Cons:

• The capacity is cut in half in favor of reliability.

RAID 0/1 drives support both modes, requiring a reformat to switch the mode. The RAID 0/1 version of the OneTouch III Turbo is expected to ship within a few weeks of the RAID 0 model.

Specifications

RAID 0
RAID 0/1

Capacity
600GB
1TB

Model
G01Y006
G01W010

Hard Drives
(two) 3.5-inch ATA

RPM
7200

Integrated Interfaces

• Firewire 800, IEEE 1394b, iLink, Up to 800Mbits/sec.
• Firewire 400, IEEE 1394a, iLink, Up to 400Mbits/sec.
• USB 2.0 and 1.1 – up to 480Mbits/sec.

Cache Buffer
16MB (each drive)

Platform
Mac and PC

Average seek time
9 ms

Sustained Transfer Rate (maximum)
Firewire 800 – 91MBytes/sec
Firewire 400 – 43MBytes/sec
USB 2.0 – 33MBytes/sec

Operating Temperature
5°C to 35°C (41°F to 95°F)

Dimensions
5.4" x 3.9" x 8.5" (136 x 98 x 217mm)

Weight
5.8 lbs (2.6 KG)

Box Dimensions
6"H x 11"W x 8.5"D (152 x 279 x 216mm)

System Requirements

Mac

• FireWire 800 requires Mac OS X 10.2.8 or
  higher and FireWire 800 (9-pin) equipped
  computer
• Apple G4 processor or greater
• Mac OS X (10.2.8 or later): 128 MB (256
  recommended) RAM or more as required by
  operating system
• CD-ROM drive
• Internet connection (for system updates)

PC

• FireWire 800 requires Windows 2000 or XP
  operating system and FireWire 800 (9-pin)
  equipped computer
• Pentium III, 500 MHz equivalent processor or
  higher
• Windows 2000 Professional, XP Professional,
  or XP Home Edition
• 128 MB (256 recommended) RAM or more as
  required by operating system
• CD-ROM drive
• Internet connection (for system updates)

Kit Includes

• External Hard Drive

• EMC® Retrospect® Express HD backup software

• 9 to 9 pin FireWire 800/1394/iLink cable

• External AC power adapter

• Installation CD with backup software and

• User Guide

• Quick Start Guide

Standard RAID levels – Wikipedia, the free encyclopedia
A classic RAID 1 mirrored pair contains two disks (see diagram), which increases … Some older RAID 1 implementations would also read both disks …
en.wikipedia.org/wiki/Standard_RAID_levels
More results from en.wikipedia.org »

RAID Level 1
Description: RAID 1 is usually implemented as mirroring; a drive has its data duplicated on two different drives using either a hardware RAID controller or …
www.pcguide.com/ref/hdd/perf/raid/…/singleLevel1-c.html

AC&NC | RAID.edu – RAID Levels – RAID Level 1 – RAID 1
Complete description and an easy-to-understand diagram of RAID level 1. Advantages and disadvantages of RAID 1 are also discussed.
www.acnc.com/04_01_01.html

RAID 1 (mirror RAID) Explained
Help: RAID 1, Mirrored Hard Disks Explained and Defined.
www.bestpricecomputers.co.uk/glossary/raid-1.htm – Similar

Why is RAID 1+0 better than RAID 0+1?
21 Jan 2009 … Of late I’ve heard much talk about RAID 1+0 being better than RAID 0+1, but never got a good answer why. Leah and I started talking about …
aput.net/~jheiss/raid10/

What is RAID? – A Word Definition From the Webopedia Computer …
4 Feb 2008 … Level 0+1 — A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over …
www.webopedia.com/TERM/R/RAID.html

RAID1 – Mirroring
Considering the previous RAID 1 configuration, assume that da1 has failed and now needs to be replaced. To replace it, determine which disk has failed and …
www.freebsd.org/doc/en/books/…/geom-mirror.html

RAID-1, Part 1
What it is, when to use it, how to make a RAID-1 device for an ext2 partition.
www.linuxjournal.com/article/5653

High Performance SCSI & RAID: What is RAID ?
Five types of array architectures, RAID-1 through RAID-5, were defined by the Berkeley paper, each providing disk fault-tolerance and each offering …
www.staff.uni-mainz.de/neuffer/scsi/what_is_raid.html

Standard RAID levels – Wikipedia, the free encyclopedia
A RAID 0 can be created with disks of differing sizes, but the storage space added to … RAID 0 implementations with more than two disks are also possible, …
en.wikipedia.org/wiki/Standard_RAID_levels
More results from en.wikipedia.org »

RAID Level 0
Common Name(s): RAID 0. (Note that the term “RAID 0″ is sometimes used to mean not only the conventional striping technique described here but also other …
www.pcguide.com/ref/hdd/perf/raid/…/singleLevel0-c.html

What is RAID 0? Striping and RAID O explained
RAID 0, RAID O explained, striped hard disks, striping hard disks in RAID.
www.bestpricecomputers.co.uk/glossary/raid-0.htm – Similar

What is RAID? – A Word Definition From the Webopedia Computer …
4 Feb 2008 … Level 0+1 — A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over …
www.webopedia.com/TERM/R/RAID.html

Beginners Guides: Installing RAID on a Desktop PC – PCSTATS.com
Abstract: With the right number of identical hard drives, motherboards that support RAID can choose from RAID 0, RAID 1, and sometimes even RAID 0+1 for …
www.pcstats.com/articleview.cfm?articleID=830

AC&NC | RAID.edu – RAID Levels – RAID Level 0 – RAID 0
Complete description and an easy-to-understand diagram of RAID level 0. Advantages and disadvantages of RAID 0 are also discussed.
www.acnc.com/04_01_00.html

OCZ Vertex SSD RAID-0 Performance | OCZ Vertex RAID-0,OCZ Vertex …
But what if we put two Vertex SSDs into a striped RAID-0 array? Benchmark Reviews tests the speed and bandwidth of two OCZSSD2-1VTX120G SSDs against the …
benchmarkreviews.com/index.php?option=com…

The PhotoFast CR-7200 MicroSDHC RAID-0 CF adapter
Now this is a good idea: RAID together four 16GB MicroSDHC cards for a fast, 64GB Compact Flash card. I guess in theory …
www.crunchgear.com/…/the-photofast-cr-7200-microsdhc-raid-0-cf-adapter/

The Software-RAID HOWTO: RAID setup
The chunk-size affects read performance in the same way as in RAID-0, … On RAID-5, the chunk size has the same meaning for reads as for RAID-0. …
tldp.org/HOWTO/Software-RAID-HOWTO-5.html

Not familiar with the AIX differences but on SCO you don’t get any messages if what you attempt to extract doesn’t match what is on the tape. It only shows successful extracts.
You could make a listing of what is on the tape so you can be sure you are extracting what is stored on it. Try it as tar -tvf /dev/rmt1 > /tmp/tapefiles.
What happens with tar -tvf /dev/mt1 ?
You generally can abort the long process by popping the tape when you get the info you need.

Hi Sammy! First of all thank you for your reply!
That’s the "funny" think, I succeed to make a listing of what is on the tape using the cammand: tar -tvf /dev/rmt1
But when I try to restore .. nothing.

I had suggested the dump to /tmp so you would have a total listing stored rather than having to list it via tar each time you wanted to know the contents.
tar is persnickity (best word I know to describe it) in how it requires input commands.
To get familiar with it I suggest (if you have a blank tape) that you do something like tar -cvf /dev/rmt1 /etc so you can see how it looks and works under conditions you know.
The ./ in front of the files is significant, just don’t remember the causes and how it relates to creating and extracting. You may have help in manual pages, assuming you have them. Try "man tar" and see if something comes up. Everybody ought to know how tar works, but after probably 10 years of using a "super tar" I’ve forgotten most of the details.

Thank you for those interesting ways, Sammy!
I will give a try with a new tape and re-read the f.. manual

And to get help from people who are familiar with the OS and the specific commands for the version you are using might I suggest that you post in one of the unix-aix forum.