Can Unraid be forced to mount an MD (raid) either as a disk, cache drive or parity drive?

Yes, assuming the raid is controlled by a hardware controller, not a software controller based raid. Several people on this forum use RAID0 volumes as parity drives, and RAID1 volumes as cache. If your RAID controller was less than 2 or 3 hundred US$, chances are it's software based.

I was more suggesting using mdadm to create a software raid1 array (primarily for cache)...i figured the hardware approach wouldn't be a big deal being that the system really doesn't know what the hardware controller has up it's sleeve. I know that linux can have nested arrays...is there a way to tell unraid to just use an array for a cache drive?

 

As a side note, I've seen on the forum that emhttp isn't ran on full slackware installs...so there must be a manual way to modify unraid configs without the web interface...right?

I was more suggesting using mdadm to create a software raid1 array

Not possible AFAIK.

I was more suggesting using mdadm to create a software raid1 array

Not possible AFAIK.

 

It is not possible as unraid replaces the normal Linux md-drivers with the unraid flavor.

Are there any third party drivers/utilities that you've heard of that would keep a real time mirror of a drive in the background that could just watch the cache drive?

None that I know of, but the delayed feature of a "cache pool" will provide fault tolerance. It was slated for release with v5.0 but was pushed back.

any guess on how far back? I see the release was going to go slack 14 with the new samba too.

any guess on how far back? I see the release was going to go slack 14 with the new samba too.

 

We have not been given a time frame.

 

Are there any third party drivers/utilities that you've heard of that would keep a real time mirror of a drive in the background that could just watch the cache drive?

 

In the mean time you could run an hourly rsync from one drive to another.

You could also change the mover to run hourly.

 

The other option is to use a hw raid controller. I've used areca with success.

I purchased a 2 drive arc-1200 on ebay for less then $100.

 

The areca supported a hybrid safe array arrangement.

with 2 drives I had a RAID0 parity drive(volume) and a RAID1 cache drive(volume).  Worked well for years.

 

There was competition between cache and parity usage when moving large files, In any case it worked well for my needs.

Three alternatives to mirroring that I'm researching that monitor the cache drive in real time and sync it to the mirror cache drive. unison, lsyncd, and csync2....csync2 seems much higher level (clustering), unison seems to be better for client/server...

 

anyone had any experience with any of these apps?