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Here's the scenario:

I am building a computer that will act as a network storage device for local networked users, and a source code repository and backup device for remote users. The machine will also be backing up to a third-party backup service (Carbonite) via internet connection.

The machine contains (1) SSD drive, (2) 2TB HDD drives, and (1) DVD drive.

  • The SSD drive will contain the OS and program files
  • The (2) HDD drives will run in RAID-1 configuration (mirrored) and serve as data storage.
  • The DVD drive will seldom be used and is inconsequential.

My motherboard has (2) SATA 6.0gb/s ports, and (4) SATA 3.0gb/s ports.

My inclination is to use (1) 6.0/s port for the SSD drive. Since it's solid state, it deserves the faster port. But this leaves only (1) 6.0/s port open. I would like to take advantage of the other 6.0/s port, but not at the expense of the operation of the RAID configuration.

Can I run the mirrored HDD drives, one on the (1) 6.0/s port left, one on an open 3.0/s port? Will this lead to problems in the short or long term?

I don't know well enough about the mechanics of RAID... but I think I ought to put them both at 3.0/s, operating at similar speeds. My fear is that if I install them one at 3.0/s and the other at 6.0/s, and a user is writing a large file to the HDD drive, it will (in theory) take twice as long to write to the drive on the slower transfer port as it will the faster. And if this is happening simultaneously for many users, over long periods of time, the slower drive will be far behind, negating the benefits of mirrored RAID configuration.

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2 Answers 2

up vote 2 down vote accepted

You're okay connecting the two drives to ports at different speeds. Yes, it means that writes will be at 3Gb/s speeds, but reads will be at 9Gb/s speeds (assuming the drives can keep up), and you probably do a lot more reads than writes.

It is never guaranteed that the two drives will stay in any kind of lock step. They're spinning at slightly different speeds, take slightly different times to seek, and so on. The RAID implementation knows how to deal with this.

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Thank you for your input! I hadn't even considered read vs. wite –  Set Sail Media Feb 25 at 3:16

Just for my sanity and added redundancy I'd get a second SSD (since you seem to be running some critical stuff here).

Put the two HDDs on the 3GB ports and install the OS there - RAID 1. Use this for automated backups during off-peak hours. Performance wont be a big deal for the process if it's all happening behind the scenes automatically.

Put the two SSDs on the 6GB ports and make that your data partition - RAID 1. Use this for your code repo where your builds/commits/etc could result in a lot of active wait time. You want this to be as fast as possible.

As for the network storage - this will depend on the usage. If you need more speed for the repo then toss the network storage onto the HDD array. If the network storage is going to need more speed and the repo is being used infrequently then it can share the SSD array.

Also, depending on the amount of usage you may want to set the Carbonite setting for what I think is titled "Use less network resources" which will limit the bandwidth it consumes - saving it for what actually needs it on that box.

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