(Solved) What is the best method of setting up software RAID-0 for cache drive?


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While doing research for setting up Unraid, I saw a command switch for setting up the cache drive as a software RAID-0...  But I didn't save it, and now my Google-Foo is coming up short on finding it again...

 

I have a Asus ROG z270 board and am trying to use Unraid to merge my ancient NAS and my gaming box, to boost the general speed of the NAS and improve write performance from the Windows Gaming VM...

 

I have already got 2 Samsung 960 EVO m.2 drives installed and would like to use them as a RAID-0 cache drive as well as the storage location for the main drive on the Windows gaming VM...

 

I have already switched the BIOS to use AHCI instead of Intel RST, and cleared the drives for Unraid...  The default GUI only allows them to be used as RAID-1, and I don't know the commands that Unraid supports to create an software RAID-0 that can then be added to the Unraid GUI...

 

I appreciate your help in advance :-D

Edited by Warrentheo
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  • 4 months later...
15 hours ago, sekrit said:

What was it that worked perfectly?  I am trying to use RST for my system as well (but only when booting outside of unraid)...

 

You would have to flip the bios setting for RST every time you wanted to switch between unRaid and RST, since RST doesn't work in linux/unRaid...  Too much hassle or risk of accidentally wiping something you didn't want to wipe IMO...

 

I just have mine set with RST disabled...

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22 hours ago, Warrentheo said:

 

You would have to flip the bios setting for RST every time you wanted to switch between unRaid and RST, since RST doesn't work in linux/unRaid...  Too much hassle or risk of accidentally wiping something you didn't want to wipe IMO...

 

I just have mine set with RST disabled...

Ok... soooo, I'm stuck.

 

I have entered safe mode three different ways(prompt, shutdown-shiftKey, and command prompt.  When I enter UEFI and switch to AHCI, I only get a black screen, a few icon flashes, and return to uefi.

 

When I do, I check boot order, I tried both m.2, with no luck.

 

I always have to return to RST raid to assure that I do not destroy my install for no reason.

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First, you need to make a choice, Linux/unRaid and Intel RST are almost mutually exclusive...  It is technically possible to run them on the same machine, but the changes you would need to make to make sure you don't accidentally delete something get complicated and IMO are not useful...

 

At its core Intel RST is the same software RAID that has been around for much longer than RST.   It has been tweaked, and is much faster than old software raid, as well as allowing unusual RAID configs such as cache drives and Optane support... But all of those require a software driver and Intel currently only writes those for Windows...  The reason they don't write one for Linux is because things like unRaid exist, making writing their own redundant...  Unraid replaces all those...  The minor speed loss is more then made up for in flexibility IMO...

 

Once you switch to AHCI, you will most likely need to wipe the drives to get them to work again...  You will also need to turn off BIOS settings that were only meant for Windows, such as Intel RST, Fast Boot, and Secure Boot...  It also helps to disable CSM and make sure your USB drive is UEFI enabled...

 

As you can see, you will need to make a choice and prepare before actually flipping this over...  I still run Windows in a guest VM, and run it off the RAID0 Cache drive in unRaid...

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  • 2 years later...
On 6/21/2018 at 5:14 PM, Warrentheo said:

At its core Intel RST is the same software RAID that has been around for much longer than RST.   It has been tweaked, and is much faster than old software raid, as well as allowing unusual RAID configs such as cache drives and Optane support... But all of those require a software driver and Intel currently only writes those for Windows...  The reason they don't write one for Linux is because things like unRaid exist, making writing their own redundant...  Unraid replaces all those...  The minor speed loss is more then made up for in flexibility IMO...

(Boldface mine.)

 

Just a small factual correction: Linux is perfectly capable of using Intel RST logical drives. Typically, each physical disk is seen as a normal block device (/dev/sd*), while the RAID drives are visible as logical drives:

# lsblk -M -o NAME,FSTYPE
    NAME      FSTYPE
┌┈▶ sda       isw_raid_member
┆   ├─sda1    ntfs
┆   ├─sda2    ntfs
┆   └─sda3    ntfs
└┬▶ sdb       isw_raid_member
 ┆  ├─sdb1    ntfs
 ┆  ├─sdb2    ntfs
 ┆  └─sdb3    ntfs
 └┈┈md126     
    ├─md126p1 ntfs
    ├─md126p2 ntfs
    └─md126p3 ntfs
 

Here, a mirrored pair across sda and sbd (note the type is “isw_raid_member”) has three partitions, available to mount via /dev/md126p{1..3}.

 

However, just as on Windows, Linux can’t use these drives if AHCI rather than RST is selected in the BIOS or EUFI. So effectively the point is correct as far as Unraid goes.

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