2025-05-05

the advantages and disadvantages of RAID 5E

DATARECOVERYUNION.COM14 mins

RAID 5E with an E that stands for Enhanced, RAID 5E is a RAID 5 array with a hot spare drive that is actively used in the array operations. In a traditional RAID 5 configuration with a hot spare, the hot spare drive sits next to the array waiting for a drive to fail, at which point the hot spare is made available and the array rebuilds the data set with the new hardware. There are some advantages to this operational method:

  • You know for a fact that the drive that would have been used as a hot spare is in working order.
  • There is an additional drive included in the array, thus further distributing the array’s I/O load. More spindles equals better performance in most cases. RAID 5E can perform better than typical RAID 5.

There are a few disadvantages associated with RAID 5E as well:

  • There is not wide controller support for RAID 5E.
  • A hot spare drive cannot be shared between arrays.
  • Rebuilds can be slow.

The capacity of a RAID 5E array is exactly the same as the capacity of a RAID 5 array that contains a hot spare. In such a scenario, you would “lose” two disks’ worth of capacity — one disk’s worth for parity and another for the hot spare. Due to this fact, RAID 5E requires that you use a minimum of four drives, and up to eight or 16 drives can be supported in a single array, depending on the controller. The main difference between RAID 5 and RAID 5E is that the drive that would have been used as a hot spare in RAID 5 cannot be shared with another RAID 5 array; so that could affect the total amount of storage overhead if you have multiple RAID 5 arrays on your system. Figure A gives you a look at a RAID 5E array consisting of five drives. Take note that the “Empty” space in this figure is shown at the end of the array.

A RAID 5E array with five drives

A RAID 5E array with five drives

When a drive in a RAID 5E array fails, the data that was on the failed drive is rebuilt into the empty space at the end of the array, as shown in Figure B. When the failed drive is replaced, the array is once again expanded to return the array to the original state.

 

Fig_B_Lowe052307

A RAID 5E array that has been rebuilt into the hot spare space

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Hard Disk Details(10)

DATARECOVERYUNION.COM06 mins

Matching Serial Numbers on Hard Drives
This link is where I keep track of documentation on how each hard drive needs to be matched for a working donor drive.  I get this any where I can, use it if you can, and if you happen to find something out please let me know so I can add it to the collection!

NOTES:
Drives with the same model number can still have different numbers of heads, therefore the board is different. It is possible to identify the number of heads in a drive: Maxtor,Quantum, Seagate from the serial numbers:

REFIRBUSHED DRIVES
REFIRBUSHIED drives cannot be used as a donor drive. Head 0 is the bottom head and could be bad. And substandard parts are often installed. It is very difficult to match a refirb drive to a good drive with the same problems. This also makes it difficult to make repair a refirb drive.

QUANTUM
Quantum – the third number in the serial number shows the headsQuantum = HA code must match

SEAGATE
Seagate – the third SYMBOL in serial number represents the heads. Seagate’s sometimes have extra heads and when one is refurbished it is possible to turn off a bad head and turn on an alternate one and then the firmware number revision might change.

FUJITSU
Fujtsu needs the first xx-Xxxx to match

IBM and HITACHI DRIVES – Usually the same driveIBM MLC codes have to match

HITACHI
Hitachi ATMR 80gigs fails mostHitachi 3.5 – Firmware code needs to matchHitachi 2.5 – PCB rev has to match

WESTERN DIGITAL DRIVES
DCM codes for the (5th??? And) 6th numbers must match.No Western Digital drives with the letter R in the code. EB and BB models.Western Digital Drives EB and BB have the head stack affixed from the lid. Western Digital the sixth char in the model is the cache. U = 2meg V=8meg

SAMSUNG
Samsung the 4th Char in the alpha code on the label on the rear side needs to matchSamsung the 7th char in the model is the size of the buffer H=8megs

MAXTOR DRIVES
The second number of the serial number represents the number of heads Maxtor needs the 2nd and 3rd char to match:

Hi you all, this is the answer I received directly from Maxtor
Dear Mr. Robert,… here is the paragraph that deals with your model type (DiamondMax Plus 9):
For the following Maxtor hard drive models: Fireball 3, DiamondMax 16, DiamondMax Plus 8, DiamondMax Plus 9, Diamond Max 10 and all MaxLine products there is also a GTLA Number on the model (next to barcode on the bottom of the drive). Format 1Y222J2223322. 1, 2 and 3 stand for numbers, Y and J for letters. The numbers 1 and 3 as well as the letter Y need to be identical to be able to replace the PCB on these drives.  This number can be found on the large sticker on the top of the drive.

Unfortunately we cannot give you any more information than this. Any of your DiamondMax Plus 9 drives could possibly have a matching PCB, however it is most likely to be an older one as the drive in question is almost 3 years old.

Kind regards,
Gisela Schubert Technical Support
Maxtor Ireland Ltd.

copied from: http://forum.hddguru.com/howto-how-to-replace-maxtor-calypso-iii-board-vt5977.html

Serial Number on Hard Drive
The boot sector in the FAT32 partition

The boot sector in the FAT partition
The data contained in the boot sector after the OEM name string is referred to as the BIOS parameter block or BPB

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Data Backup Glossary (Letter Q)

DATARECOVERYUNION.COM07 mins

Data Backup Glossary (Letter Q)RAID
See redundant array of independent (or inexpensive) disks.

RAIN
See redundant array of independent nodes.

Raised floor
A type of flooring supported by a metal grid and typically used in data centers. Raised flooring can be removed in pieces to allow for cabling, wiring, and cooling systems to run under the floor space. When the floor is raised, it usually can accommodate space for walking or crawling in.

Recovery
The recreation of a past operational state of an entire application or computing environment. Recovery is required after an application or computing environment has been destroyed or otherwise rendered unusable. It may include restoration of application data, if that data has been destroyed as well.

Recovery point objective
Recovery point objective (RPO) is the maximum acceptable time period prior to a failure or disaster during which changes to data may be lost as a consequence of recovery. Data changes preceding the failure or disaster by at least this time period are preserved by recovery. Zero is a valid value and is equivalent to a “zero data loss” requirement.

Recovery time objective
Recovery time objective (RTO) is the period of time after an outage in which the systems and data must be restored to the predetermined recovery point.

Red Hat Global File System
Red Hat Global File System (GFS) is an open source cluster file system and volume manager that executes on Red Hat Enterprise Linux servers attached to a storage area network (SAN). It enables a cluster of Linux servers to share data in a common pool of storage to provide a consistent file system image across server nodes. Red Hat Global File System works on all major server and storage platforms supported by Red Hat.

Redundancy
The inclusion of extra components of a given type in a system (beyond those required by the system to carry out its function) for the purpose of enabling continued operation in the event of a component failure.

Redundant array of independent (or inexpensive) disks
Redundant array of independent (or inexpensive) disks (RAID) is a category of disk drives that employ two or more drives in combination for fault tolerance and performance. RAID disk drives are used frequently on servers but aren’t generally necessary for personal computers. RAID allows you to store the same data redundantly (in multiple places) in a balanced way to improve overall performance.

Redundant array of independent nodes
Redundant array of independent nodes (RAIN) is a data storage and protection system architecture. It uses an open architecture that combines standard computing and networking hardware with management software to create a system that is more distributed and scalable. RAIN is based on the idea of linking RAID nodes together into a larger storage mechanism. In a RAIN setup, there are multiple servers, each with disk drive and RAID functionality, all working together as a RAIN, or a parity or mirrored implementation. RAIN may also be called storage grid.

Remote offices/branch offices (ROBOs)
Refers to corporate offices externally connected to a WAN or a LAN. These offices will often have one or more servers to provide branch users with file, print, and the other services required to maintain the daily routine.

Replicate
(n.)  A copy of a collection of data.
(v.) The action of making a replicate as defined above.

Restore
To bring a desired data set back from the backup media.

Rotational latency
Also called rotational delay, the amount of time it takes for the desired sector of a disk (for example, the sector from which data is to be read or written) to rotate under the read-write heads of the disk drive. The average rotational latency for a disk is half the amount of time it takes for the disk to make one revolution. The term typically is applied to rotating storage devices, such as hard disk drives and floppy drives (and even older magnetic drum systems), but not to tape drives.

RPO
See recovery point objective.

RTO
See recovery time objective.

Run length limited
Run length limited (RLL) is an encoding scheme used to store data on newer PC hard disks. RLL produces fast data access times and increases a disk’s storage capacity over the older encoding scheme called MFM (modified frequency modulation).

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Top 20 Most Popular External Hard Drives on Amazon.com

DATARECOVERYUNION.COM06 mins

External Hard Drives External hard drives are ideal for backing up your hard drive or storing additional media separately from your main hard drive. Photos, videos, and digital music have all become so popular in recent years that people need a place to put it all. CDs and DVDs do not have the capacity to hold PC backups and are not all that convenient. However, the prices of external hard drives have come down so much that they are perfect for backing up your important data.

The two most common interfaces for hooking up external drives to your computer are USB and FireWire with eSata now becoming popular also. USB has been around for years and are standard on just about all computers today while FireWire ports are newer and if you use a digital video camera with your computer you probably already have one. In terms of access speeds the latest eSata standard offers the fastest connection however that comes with a price. USB 2.0 and Firewire can cover most of your general needs without having to upgrade your system with a new eSata card. Any of the interfaces will do the job however be sure to purchase an external hard drive with the same type of port that your computer has.

WD Elements 640 GB USB 2.0 Portable External Hard Drive

        (Price: $149.99 Price on Amazon.com: $98.92)

Seagate FreeAgent Go 500 GB USB 2.0 Portable External Hard Drive

        (Price: $139.99 Price on Amazon.com: $89.00)

Iomega Prestige 1 TB USB 2.0 Desktop External Hard Drive

        (Price: $172.99 Price on Amazon.com: $99.99)

Toshiba 500 GB USB 2.0 Portable External Hard Drive

        (Price: $93.99 Price on Amazon.com: $82.44)

WD Elements 1.5 TB USB 2.0 Desktop External Hard Drive

        (Price: $169.99 Price on Amazon.com: $117.82)

Toshiba 320 GB USB 2.0 Portable External Hard Drive

        (Price: $99.99 Price on Amazon.com: $60.00)

WD Elements 1 TB USB 2.0 Desktop External Hard Drive

        (Price: $129.99 Price on Amazon.com: $97.95)

WD My Passport Essential SE 1 TB USB 2.0 Portable External Hard Drive

        (Price: $199.99 Price on Amazon.com: $149.00)

WD My DVR Expander 1 TB eSATA Desktop External Hard Drive

        (Price: $159.99 Price on Amazon.com: $129.00)

LaCie d2 Quadra Hard Disk 1 TB USB 2.0/FireWire 400/800/eSATA Desktop External Hard Drive

        (Price: $164.99 Price on Amazon.com: $154.99)

Seagate FreeAgent Go 500 GB USB 2.0 Portable External Hard Drive

        (Price: $139.99 Price on Amazon.com: $89.00)

Seagate Expansion 500 GB USB 2.0 Portable External Hard Drive

        (Price: $115.99 Price on Amazon.com: $79.99)

Iomega eGo Mac Edition 500 GB USB 2.0/FireWire 400/800 Portable External Hard Drive

        (Price: $140.99 Price on Amazon.com: $125.99)

Iomega Prestige 1.5 TB USB 2.0 Desktop External Hard Drive

        (Price: $147.99 Price on Amazon.com: $119.99)

Seagate Expansion 1 TB USB 2.0 Desktop External Hard Drive

        (Price: $115.99 Price on Amazon.com: $89.99)

Iomega Prestige 320 GB USB 2.0 Portable External Hard Drive

        (Price: $115.99 Price on Amazon.com: $79.30)

Iomega Prestige 500 GB USB 2.0 Desktop External Hard Drive

        (Price: $82.99 Price on Amazon.com: $74.44)

Seagate FreeAgent Go 250 GB USB 2.0 Portable External Hard Drive

        (Price: $89.99 Price on Amazon.com: $59.82)

Seagate Expansion 250 GB USB 2.0 Portable External Hard Drive

        (Price: $75.99 Price on Amazon.com: $58.99)

WD Elements 500 GB USB 2.0 Portable External Hard Drive

      (Price: $129.99 Price on Amazon.com: $89.99)

Note: Your backup drive should have a capacity at least as big as your computer’s largest hard drive. That will leave you with plenty of room to back up your important files or mirror/clone your current drive. You can also buy an external hard drive case and mount an internal hard drive inside it. This method will give you a choice of brands and models, and if anything goes wrong with your internal hard drive, you can simply install the external one inside your computer to replace it.

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