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external(eSATA) RAID 1 mirrors and port multiplier

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  • Laptops
  • NAS / RAID
  • Storage
  • Port
Last response: in Storage
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September 30, 2014 6:03:04 PM

If I want to set up an external RAID 1 drive (2x 2tb HDs) that connects to my laptop via eSATA, do I need a port multiplier for that eSATA connection? Or will my laptop recognize the single RAID volume correctly (even though it's made of 2 disks).

My understanding is that the laptop will see a maximum of 1 disk through that eSATA port (RAID or not), but if I try to add other logical disks (in a 4-bay enclosure for example) the laptop will not recognize any additional disks due to it not having a port multiplier. Is this correct?

More about : external esata raid mirrors port multiplier

a b D Laptop
a b G Storage
September 30, 2014 6:15:45 PM

External eSata RAID enclosures are seen as a single hard drive in a lot of instances - as the RAID controller is built into the enclosure. Not all are built this way - it would depend upon the make/model.

What was the purpose for a RAID1 with 2 drives on a home PC? The reason I ask - unless you are doing a "project for fun" - I always recommend against RAID in the home....I use it all the time at work on the servers I work on. These servers typically have a RAID controller that runs anywhere from $1,000 to $25,000 - plus the cost of the drives (usually 10-20 drives in the enclosure). I generally use RAID5 or RAID 10 - depending upon the setup. I keep extra drives on hand in case of failure (it happens quite often with that many drives).

For home use - it is expensive - and generally more of a headache than a good thing. My main rig has a 128GB SSD (OS & Programs), a 1TB HDD (WD-Black for data) and a backup drive (WD-Black). I take an image of the OS drive in case of failure, and I use SyncBack Free to backup the data drive (I also backup 3 other computers on my network to this drive). The only additional cost was the extra backup drive (software was free), and I backup all drives.
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September 30, 2014 7:31:19 PM

Thanks for your reply, and I should clarify, sorry. The laptop in question will actually be the NAS host (setup with FreeNAS right now). It's a decent laptop from about 4 years ago (i3, 4GB RAM).

I was thinking RAID 1 for a few reasons. It's my wife's and my home network, and the NAS will serve as both a backup place and a repository for photos, videos, important docs, data, and music. I will be putting a large photo library on there and would like to have it only there, as in having no copies of it on any of our personal computers. I know a RAID mirror doesn't really replace having a backup, but I was thinking the redundancy would suffice for our needs (instead of a normal backup) for something like that photo library and some of my old audio work (music, stems, lots of WAVs and AIFFs). The other reason is that this NAS is a fun project in re purposing a retired laptop, and I would like to get a bit of experience with RAID mirrors and setting them up, seeing how they work for my pro-sumer uses, etc.

The other part of the NAS would be just a normal drive and would serve for basic backup purposes from our personal PCs.

The RAID mirror would be attached to the laptop NAS via eSATA. I've been informed that the laptop (due to not supporting port multipliers) will not host more than 1 drive on that eSATA line, so I was wondering if a 2x drive RAID 1 setup would work with it or not (1 logical volume, but 2 physical ones).
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Related resources
a b D Laptop
a b G Storage
September 30, 2014 7:37:24 PM

If the laptop is limited on the eSata port - I don't think multiple drives would be supported that way.

You might want to consider this: http://www.2brightsparks.com/freeware/freeware-hub.html

This allows you to "synch" two drives (you use drive "A" as the primary storage - the software synchronizes it to drive "B") It can be done real-time or as a job that runs over night. Then you wouldn't need RAID (it would basically be the same thing). The beauty of this setup - If either drive dies, you just change the share to the other drive. You have zero down time (a RAID rebuild will take 30 minutes to several hours). The 2nd drive can be in a USB connection, and the primary storage drive be a standard eSata setup.
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September 30, 2014 8:26:57 PM

Yeah, something like that may work. I'll have to look into it some more.

So, that eSATA port can really only interact with 1 drive then, whereas if I plugged a filled 4-bay enclosure into a USB port, the computer would see and interact with all of the drives?
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Best solution

a b D Laptop
a b G Storage
September 30, 2014 8:28:40 PM

The USB port should work - although it will be slower. A USB-3 would be better....but still not the speed of SATA III.
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