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Hybrid Internal/External Raid Array

Last response: in Storage
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December 1, 2008 8:10:30 PM

Hello,

I just have 3 questions (?#?)
However, if you would like to add more details, it would be appreciated ;-)

I am trying to put the components together to build a RAID array.
I am considering 3 different schemes, depending on the limiting characteristics (Speed & Compatibility) VS. Security of the Array.

(I) Raid Options: 1E, 10, 50, 5EE, or 60
http://publib.boulder.ibm.com/infocenter/eserver/v1r2/i...


This is critical because in the event that the external enclosure loses power, this only interrupts the mirrored side of the array.
- RAID 10 = uses no parity calculations, making it more suitable for HD Video
- I am considering the non-parity RAID types for their performance (1E, 10)

- RAID 50 or 60 = faster than 5 and 6 alone, but a trade-off of capacity for write performance (if it is fast enough in this configuration, it may be a migration path later)
- The mirrored sets are attractive in the event that the A)power, B)external power supply, or C)SAS cable fails I can still have a working set internally or vice versa (10, 50, 60) [It’s not stated that 0+1 is supported]

- RAID 5EE is attractive for it’s built in Hot-Spare architecture
http://publib.boulder.ibm.com/infocenter/eserver/v1r2/i...

(?1?) Is it possible to configure where the drives align in the array?
[For example, it is my intention for the array to be built by mirroring across the miniSAS cables (meaning that a mirrored set will be both inside and external)

(?2?) Or would this already be the default configuration?]


(II) Controller:

Adaptec 51245 8-lane PCIe / RAID level 0, 1, 1E, 5, 5EE, 6, 10, 50, 60, JBOD (Unique = 5EE)
Ports: 3 internal SFF-8087, 1 external SFF-8088
Dual core
1.2 GHz RAID on Chip 512MB cache
http://www.adaptec.com/en-US/support/raid/sas_raid/SAS-...

Areca ARC-1680ix- RAID level 0, 1, 10(1E), 3, 5, 6, 30, 50, 60, Single Disk or JBOD (Unique = 3, 30, Single Disk)
With the same connections but with a 1200 MHz Intel IOP348 I/O Processor
And included 512MB of on-board DDR2-533 memory with ECC protection (upgradeable to 4GB)
http://www.amug.org/amug-web/html/amug/reviews/articles...

(?3?)Core2 on chip Vs. 4GB memory
-? Which is more critical to performance for the nested RAID levels I am considering, a faster processor, or more ram?
Adaptec claims they are the fastest when compared to Areca, However this is assuming they used the default Areca Ram setup of 512MB (I am willing to upgrade to 4GB) also, not sure of the real-world relevance of these tests.
http://www.adaptec.com/NR/rdonlyres/B4350D45-E31A-429E-...


I have also considered controllers from LSI, High Point, and 3Ware but I am leaning towards Adaptec or Areca, for their quality build of card, along with the responsiveness of their support services.
However I would be grateful for any recommendations that you can make based off of personal experience.

(III) Hard Drives:
I have the Seagate Drives listed below, (Seagate Barracuda 7200.11 ST3750330AS)
I would like to utilize them if at all possible (otherwise I’ll have to eBay them and start fresh!)
The compatibility white sheet for Adaptec does not list this drive as compatible (I am waiting on customer support to answer this)

(IV) External Enclosure:
There are 3 options that I am aware of:
A) Port replication
- I wish to avoid this route (what I am using currently) to avoid performance losses, additional complexity, and stability issues
B) MiniSAS to 4X SATA connectors
- This seems to provide the most direct link and closest solution to having all of the hard drives inside the server case (however it also seems to be the least common)
Example of required enclosure: http://eshop.macsales.com/item/IcyDock/MB561S4S/

C) Multi-Link (miniSAS) or Infiniband
- I don’t know if this is practically the same as option B) connection wise? There seems to be more options for this type of setup
Example of required enclosure: 8-Bay http://www.pc-pitstop.com/sata_enclosures/scsat84xt.asp
4-Bay http://www.pc-pitstop.com/sata_enclosures/x4express.asp

-What I have now: AMS DS-2350S eSATA 5 bay Enclosure W/ 3 750GB HDs Raid 0
This provides some level of redundancy, however all “Backups” of files must be done manually.
I have considered automation helping this process but I feel that I have come up with an even better solution using the RAID levels mentioned above

-What I’m migrating to: Instead of 2 separate redundant volumes, I wish to employ a single volume . . . (automated redundancy through RAID)

Objective:
While utilizing these drives internally in any Raid Configuration INSIDE my PC case would be a fairly standard operation,
The complexity I am introducing is storing ½ (or more) of a SINGLE array EXTERNALLY and utilizing a SEPARATE enclosure & power supply.
The advantage to this setup is:
1) Larger expansion than inside the PC case
2) Reduced load to the PC power supply
3) Ready access to hot swap drives in the array
4) Somewhat physical separation and redundancy (power supply)

Storage Usage:
This volume will consolidate various types of data into a single repository that can be readily searchable. (also thru indexing)
A large part of the storage will be media files, some being HD-video files that will be used in video editing. (AVCHD so more processor intense than bandwidth, however I may convert to MPEG2 before editing at which point I will be dealing with minimum bandwidth requirements)


Current System Components:
Vista Ultimate64, GIGABYTE GA-X48-DQ6 LGA 775, 3.0GHz Intel X48, E8400, [2GB X2] 4GB GeIL Evo One DDR2, [2X]Raptor WD360ADFD 36GB(OS drives - Mobo Raid1) 750GB(X7)Seagate Barracuda 7200.11 ST3750330AS



I apologize for the length of this post, I tried to organize somewhat to compensate.
Hopefully this will simplify the thread so that these details do not need to be repeated.
I value any suggestions concerning equipment, implementation, or venders with which you have knowledge or experience.
December 2, 2008 4:31:38 PM

Just a thought but Seagate now makes a 1.5TB drive. Why not sell the 750's and use all 1.5's and keep it all internal? It seems that that would eliminate several of your issues with the hybrid internal external array. Then just use raid 10 for simplicity. IMHO that would be easiest but maby that solution doesnt fit your needs.
December 4, 2008 9:15:42 AM

Update:
Both Areca and Adaptec have signed the death notice on using my current hard drives for their high end controllers. (stay tuned to eBay)
This means I am now in the market for complementary hard drives for this system.

I have asked each vender and I will also ask the forum to please recommend a set of both controller and matching hard drives.
Does anyone have any recomendations for affordable enterprize hard drives that will work here?


Justanothertechie said:
Just a thought but Seagate now makes a 1.5TB drive. Why not sell the 750's and use all 1.5's and keep it all internal? It seems that that would eliminate several of your issues with the hybrid internal external array. Then just use raid 10 for simplicity. IMHO that would be easiest but maby that solution doesnt fit your needs.


This is true, I could reach the current capacity by doubling the drive volume sizes, however, part of my intention is for future expansion (1 reason I am considering an 8-bay enclosure)
As we all know, you will fill all of your available space eventually, no matter how capacious it appears initially, the above solution is an attempt at somewhat future-proofing my system. ("somewhat")

-another side point is price/GB. At the time the I opted for the 750s because 1TB hd's were new and were at a premium price.

-considering I plan on expanding in the future, I should be able to purchase the smaller capacity drives at a better $/GB,

-also RAID requires all drives to be identical (at-least in volume)
so a large capacity investment today means a large(r) investment tomorrow to keep purchasing matching drives. (I may consider purchasing 1TB this time depending on $)

Please be aware that I am limited as to what drives will work with the RAID controller (just because there is a good deal on large capacity hard drives does not necessarily mean I will be able to use them)
!