Building a eSATA DAS

[radiogoober]

Hi all,

I am trying to figure out how to build my own DAS. I say DAS instead of NAS, because I already have a Mac mini server that acts as a file server, but my storage situation there is messy.

Currently attached to my Mac mini server:
- WD MyBook Thunderbolt Duo (2 x 3TB disks, JBOD)
- WD MyBook FW 800 3TB disk
- 2 x 1 TB USB2.0 disks

Currently, the first 3TB disk in the WD Thunderbolt Duo is my media drive. The data there is replicated by Carbon Copy Cloner (a rsync front-end) to the second 3TB disk, and also to the FW800 disk, which gives me two complete copies of my media.

I'm rapidly filling up the 3TB disk, so I want to upgrade to something more spacious. I'm paranoid about data loss, so I want to upgrade to something that will give me at least 1 full backup of my data. I'm interested in a RAID5 or RAID6 setup, but duplicated. My thoughts were:

2 x RAID5 setups - Being RAID5, if one disk fails in the array then the array can be repaired. In the off-chance that the RAID5 array fails completely, then I'd have a whole backup of the array in a second RAID5 array.

2 x RAID6 setups - The same logic as above, but with the dual disk redundancy that gives me an extra layer of security, which decreases the chance that I'd ever have to actually depend upon the second RAID6 setup.

I want about 12 TB of storage.

(Note: I am aware of things like CrashPlan, but they only allow you to seed a single 1TB drive, and my internet service caps at 220 GB / month, which means it'd take me literally years of utilizing all my bandwitch to upload multiple terrabytes of media.)

I've read lots of wonderfully written articles about setting up these types of file servers with a Linux box. However, I'm interested in taking a different approach. I already own a wonderful Mac mini that is fast, and it has a Thunderbolt port.

My hope is to build a pair of DAS that can be built into a rack mounted case, and connected directly to the Mac mini via a Thunderbolt port accessory.

With that, I thought of two different ways I could add lots of storage:

1. Lacie eSATA Hub - http://www.lacie.com/products/product.htm?id=10574 - It uses the Thunderbolt port to allow two eSATA connections to your Mac. It does *not* support port multiplication. I don't know enough about eSATA, etc, to know what this is exactly capable of. I believe that the only way to have multiple disks present themselves to the eSATA hub as a single disk is if they are in a RAID. So my belief was that I could simply buy a case, put in X number of disks, and utilize a RAID card to allow them to present themselves as a single eSATA drive. However, I can't imagine how this would work because I would believe that a RAID card would need to be connected to a motherboard, or somehow else powered, and that seems like it could get very difficult very quickly. Furthermore, the case would need a power supply for the disks, and I can't imagine that the power supply would work without a motherboard. ?

I have seen pre-built solutions, for example, this one from OWC: ( http://eshop.macsales.com/shop/hard-drives/RAID/Rack_Mount/FireWire_USB3_eSATA_1U ) It has a built in port multiplier, eSATA, and 12TB is $1200. And in essence, this is what I'm looking to build, a self-contained RAID storage device that presents itself as a single eSATA device. But this device is cheap, and that worries me. A comparable solution is offered from SonnetTech ( http://store1.sonnettech.com/product_info.php?cPath=100_120&products_id=376 ), and is $2000.

With that pre-built device, I could get 2 x 12TB units for $2400, plus the Lacie eSATA hub for $200, totalling $2600 for 24TB of rack-mounted storage.

Can it be done cheaper?

2. My other thought utilizes a Thunderbolt accessory from SonnetTech. They make something called the Echo Express PCIe Expansion Chassis, which allows you to use PCIe cards in a small box that is connected to your computer via Thunderbolt. ( http://www.sonnettech.com/product/echoexpresschassis.html ) This is more expensive than the Lacie hub, at $600 or $800 for 1 or 2 slots, respectively. With this device, I could add a RAID card (expensive?) or a card with multiple eSATA ports.

My thought was that I could buy a rackmount server case, put the disks in, and wire them to the RAID controller card, and I'd actually just leave this SonnetTech box in the server chassis (with no motherboard, seems like there'd be a lot of room), and then it would be a single Thunderbolt cable running from the Mac mini to the rackmount chassis, and that would give me all the storage space I need. This still doesn't alleviate the problem of the hard disks needing a power supply.

-

Does anything like either of my two ideas seem feasible? Basically I'm looking to build a couple of rack mounted chassises that can be hooked up via either RAID or eSATA to a Thunderbolt accessory.

 

[patrickdk]

They do make hardware raid port multipliers, that would do what you want, for the lacie esata to work.

They normally take 4 disks, and raid them into a single disk, using raid0/raid1/raid10/raid5 options.

You can't normally plug an port multiplier into one of these, but you can chain many of these together.


http://www.addonics.com/technologies/tutorial_pm.php

Last two in the first list, and the 3rd one in the second list.

 

[Aesma]

For me the problem with your current situation, and your plan, is that you have two backups of your data, but they're all at the same place, connected to the same computer. Something can still go wrong and wreck everything.

 

[radiogoober]

WOW. I did not not know that the external port multiplier thing existed. I found this one after your suggestion:

http://www.amazon.com/gp/product/B0...&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846

That looks pretty cool. I found a case with 10 internal drive spaces, and two external 5.25" bays to mount these port multipliers.

So it seems like I could buy the case, put the 2 port multipliers in, and connect 5 drives to each, set them to RAID5, and then put a powersupply in, short the green wire on the motherboard connection to a black wire, and then this would essentially be a DAS unit. (I want to avoid using a motherboard!)

 

[radiogoober]

Of course, the same company makes ready made solutions that do exactly what I'm looking for, one for example:

http://www.datoptic.com/1u-rackmount-esata-interface-hardware-raid-rm5-r5l.html

If I bought my own case, power supply, and the adapter, it'd cost just as much. Looks like I may be going with something like this.

Or this:

http://www.datoptic.com/1u-rackmount-port-multiplier-esata-host.html

Or if I want to spend more than necessary:

http://www.datoptic.com/hardware-raid-five-5-bay-1u-rackmount-esata-interface-rm5-r5.html