# RAID Technology



## peds48 (Jan 11, 2008)

Hey guys

So I am tired of having to keep recovering my files from my computer drives. A little history

I Started using Windows PC many many years ago. I have never owned a Windows PC that lasted me more than 3 years. The OS will always crash at some point or another. I will then buy another Windows PC and the same thing happened. leather, wash, repeat. Until the "light" hit me and became a proud Mac user. The Mac runs fine after 3 years, but I have lost 3 external drives thus far. last one was last week. I went with external drives with my last Windows since I did not want to lose the files again if the OS crashed since the files were on the same drive. and yes I have been able to recover files but is a pain stacking process. SO now I am thinking on RAID, but this is not my forte. So can some of you guys enlighten me with this technology and if possible provide some sample of RAID enclosures, possible one that are not expensive...

Thanks guys


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## Richard (Apr 24, 2002)

This is what I use: http://www.synology.com/products/product.php?product_name=DS213%2B&lang=us

I have two 2TB drives in RAID-1, if one drive fails, the other takes over and then you can replace the failed drive to restore redundancy. If both drives fail, you are out of luck.


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## peds48 (Jan 11, 2008)

can you explain the differences in RAID 0, 1 JBOD

That is a little expensive. I am looking some thing around the 100 range if possible


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## peds48 (Jan 11, 2008)

how about this

http://www.ebay.com/itm/Vantec-NST-620S3R-BK-NexStar-HX2R-Dual-3-5in-SATA-to-USB3-0-eSATA-RAID-Enclosure-/161091132691?pt=US_Drive_Enclosures_Docks&hash=item2581c79d13


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## Richard (Apr 24, 2002)

RAID-0 has no redundancy, it will use all available space of both drives. RAID-1, since it does have redundancy, you only get the available space of one of the drives. RAID arrays require the drives to be all the same size, if they aren't, it will base it off the smallest drive. JBOD allows you to use different size disks and use the full capacity, but you don't get redundancy (See here: http://en.wikipedia.org/wiki/Non-RAID_drive_architectures)

I've never used a RAID enclosure like the one listed there. It would depend on the RAID controller it uses, whether it will be reliable or not.


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## RunnerFL (Jan 5, 2006)

Depending upon how much space you want these are my 2 suggestions.

2 drives, use RAID 1:
http://www.amazon.com/Sans-Digital-MR2UT-MobileRAID-Enclosure/dp/B007QQ4584/ref=sr_1_1?ie=UTF8&qid=1377204450&sr=8-1&keywords=sans+digital+2+bay

4 drives, use RAID 5:
http://www.amazon.com/Sans-Digital-MobileSTOR-MS4UT-Hardware/dp/B006MB9B2E/ref=sr_1_6?ie=UTF8&qid=1377204524&sr=8-6&keywords=sans+digital+4+bay

In all of my gear I currently have 3 of the 2 drive enclosures and 2 of the 4 drive enclosures and have not had any issues with either. 2 of the 2-drive variants are hooked up to DVRs and 1 of the 4 drive enclosures is hooked up to my HR44.

With RAID 1 each drive is a mirror/copy of the other and the drives must be the same size. With RAID 5 you need 4 drives of the same size with 3 being used at all times and the 4th is a spare in case one of the other 3 fails.


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## TBoneit (Jul 27, 2006)

This is what I am using.

Two QNAP TS-220 Diskless System Network Storage
Four Western Digital Red NAS Hard Drive WD20EFRX

The total was reasonable at $806 Plus S&H
This gives me two 2Tb Network attached Storage that have mirrored drives for safety.

I tried Western Digital NAS's and they were dog slow. These run a decent speed between USB 2 and USB3.

You can be frugal or you can be safe, I chose safe. Plus these can sit anywhere there is a Ethernet Connection. Gigabit network of
course.

I went NAS so that any computer can access them. If You only have one computer then You can go USB connected.

Good Luck
TBoneit


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## P Smith (Jul 25, 2002)

RAIDs is not enough to preserve your data; anyone who works in IT knew: it's multi-tier process involved tapes, DVDs, offsite storage, etc.
Perhaps clouds nowadays.


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## zx10guy (Nov 16, 2008)

P Smith said:


> RAIDs is not enough to preserve your data; anyone who works in IT knew: it's multi-tier process involved tapes, DVDs, offsite storage, etc.
> Perhaps clouds nowadays.


+1

RAID is never considered a substitute for doing backups.

Keep in mind with RAID, you have to account for the rebuild time required when a drive does fail. The larger the drives, the longer it will take for the rebuilds to happen. So during the rebuild of the RAID volume, your data is at risk until the entire volume has been restored to full health. Also, the more drives you have in a RAID volume, the higher the probability of overall volume failure due to the statistics of more than one drive failing at a given time. Most RAID (RAID 0 excluded) can only tolerate one drive failure at a time. This is why other RAID technologies were developed such as RAID 6 which uses dual parity drives. Which leads to a clarification of a previous poster's statement about RAID 5. RAID 5 is disk striping with parity. The data is laid down across the disks in chunks with one of the disks in the RAID set storing the parity information. The parity information is data the RAID controller can use to restore the missing data from a failed drive. The reason why RAID 5 is used in many circumstances is due to it's better performance in reads (think similarities to RAID 0) and better storage efficiency. With RAID 1, the data efficiency is only 50%.

With all this said about RAID schemes, depending on your risk tolerance, one should consider a system which also supports hot spares. A hot spare is a drive which is inactive but included in the RAID setup. If a drive fails, the RAID controller will automatically bring the hot spare online and rebuild the volume with the hot spare. This is nice if you have your RAID storage out of sight or if you're not constantly monitoring the health of the RAID storage. But may not make sense to many home users as the cost/benefit may not align to their expectations. One feature which should be considered mandatory in a RAID system is the ability to support hot swapping of drives.


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## peds48 (Jan 11, 2008)

Thanks guys.

Between iCloud, Dropbox, Google Drive and Sky Drive there is not much that I loose. is more like the hassle of having to re-download everything to anew drive. At the same time is not like I have "Fort Knox" or "classified" information. I decided to get enclosure link by RunnerFL. http://www.amazon.com/Sans-Digital-MR2UT-MobileRAID-Enclosure/dp/B007QQ4584/ref=sr_1_1?ie=UTF8&qid=1377204450&sr=8-1&keywords=sans%20digital%202%20bay&tag=5336432741-20

All I really wanted was to understand more about RAID which now I have a better understanding and have some redundancy when one drive fails I can easily swap it with out the need for me to do the actual copying.

Thanks


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