Mirroring a SATA DOM with a slower drive

[Andor]

Hi there!

I've gone the SuperMicro X10 way, and I've finally bought one of their SATA DOM drives. The thing is, the board only supports one SATA DOM at a time, so if I want to mirror the boot device, I have to pair it with a different type of device.

I don't know how reading and writing works on this kind of mirror so, I have a question:

If I mirror my SATA DOM to a slower drive, as a USB stick, will the general boot and working speed resent, or only if the main drive fails?

Thanks

 

[Ericloewe]

Boot times are never a problem. It's write-heavy situations that suck on USB devices.

So, mirroring a DOM with a slower drive gains you nothing. I suggest you stick to the DOM only.

 

[Andor]

Ok, I was thinking on how to avoid downtime if the DOM breaks. Anyway, this is my home NAS and I'm not worried about 1 or 2 hours of downtime, I'm worried about data, but I got that covered with RAIDZ2.

Thanks!

 

[Ericloewe]

You can also plug in the USB drive ahead of time and then just install FreeNAS on it over IPMI if needed, after the DOM fails (DOMs are mostly reliable, though, unlike USB drives). Probably less than 30 minutes' worth of downtime, plus the time needed to download the latest FreeNAS release.

 

[TooMuchData]

I recently put two SATA DOMs on my Asrock C2750D4I and found that only one was recognized in the BIOS. Is this what you experienced (and said that the board only supports one SATA DOM at a time)?

If not, I apologize for what follows.

After much experimentation I discovered that my SATA DOMs (MV 3ME) have 20 character internal serial numbers. The 9230 controller was truncating the serial numbers at 18 characters, concluding they were the same (I surmise), and displaying only one device. I moved one SATA DOM to a port on a different (Intel) controller and both were then recognized. I subsequently tested both DOMs individually in both 9230 ports and found no problems.

Interestingly, my board only allows me to boot the device that is in the Marvel port, not the Intel port. However, the DOMs are now mirrored.

Also of interest - the serials recognized by the controllers and reported by FreeNAS bear no relationship to the labels affixed to the devices.

 

[cyberjock]

You can definitely boot from the Intel ports. There's a BIOS setting you have to change that I'm guessing you missed.