SATA Multipliers in RAID?

Matt Kenny

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Apr 10, 2014
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I have come into possession of quite a lot of 1TB Hard Drives, which I plan on using in RAID on a server system. However, I have a few questions as to how they would function under certain situations.

1. Would I be able to RAID the Hard Drives if I Connected 25 of them via 5x 1to5 SATA Port Multipliers?
2. If so, what would happen if I left 3x HDDs in a multiplier, and then added another 2 into the same multiplier after RAIDing them?
3. Would they run at a compromised speed for any reason? Do more hard drives mean slower speeds, or do the SATA Multipliers slow the speed of the HDDs?
 
Solution

Yes your speed would be compromised. SATA port multipliers work by letting the SATA port take turns talking to each drive. So basically your RAID array could never be faster than a single drive, and most likely would be much slower.

In other words, the only reason to do this would be for extreme redundancy (RAID 6). You're probably better off using them as JBOD and using Windows' storage pool feature to combine them for capacity and redundancy.

You're also going to run into problems starting up a system with this many drives. While HDDs only use about 5-10 Watts on average...


First....you have to determine exactly what RAID level you're talking about.
25 drives in a single RAID array sounds like a recipe for disaster.
 

Yes your speed would be compromised. SATA port multipliers work by letting the SATA port take turns talking to each drive. So basically your RAID array could never be faster than a single drive, and most likely would be much slower.

In other words, the only reason to do this would be for extreme redundancy (RAID 6). You're probably better off using them as JBOD and using Windows' storage pool feature to combine them for capacity and redundancy.

You're also going to run into problems starting up a system with this many drives. While HDDs only use about 5-10 Watts on average, they can draw 20-60 Watts when spinning up. To prevent a huge power spike from spinning up all the drives simultaneously, motherboards are programmed to spin them up in a random sequence. (1) I'm not sure what a port multiplier will do to this spin-up sequence, and (2) either you'll be waiting a very long time for all 25 drives to spin up, or your power supply is going to get hit by a huge power spike as the system attempts to quickly spin up so many drives.

I'd forget the port multiplier idea, keep as many drives as you can fit into your system as-is, donate the rest to a computer charity service, and if you need capacity buy a 4-8 TB drive with the tax deduction money from the donation. If you were thinking of a 25 TB file server left on 24/7, the power consumption of 25 hard drives (150 W at 6 W each) would result in $150/yr of electricity used if you pay the U.S. average of 12 cents/kWh. Buying fewer large-capacity drives would actually be cheaper after a few years.
 
Solution