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SHR-1 discspace


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Hej all.


I've just installede the Xpenology on a virtual machine to test it out before I install it on my main server.

But I seem to have a problem with the disc size of SHR-1.

I have a bunch of 4 tb and 2 tb discs, to simulate that, I created 2 40gb discs and 2 20gb discs. 

According to synology's raid calculator it should give me 80gb available space, with 40gb used for protection

BUT, when I actually make the SHR-1 raid in xpenology, I only get aroud 60 gb free space.

I looks like it treats it as a raid 5.


I have attaced the images from synology raid calculator, and the image from my Xpenology.


Can anyone explain this to me ?

syno raid calc.JPG

xpenology SHR-1.JPG

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  • 2 weeks later...

to be more precise about the cause

synology has a (small) usb bootloader (containing kernel and basic driver to load file system, like dedicated boot partition in earlier linux days) and the "system" (dsm) is a raid1 over all installed disks

also there is a 2.3 GB swap partition, also as raid1 on all disks

to boot up dsm it just needs one working disk left in the system


to use a new added disk in dsm (like using a disk to extend a raid set) you have to initialize it fist, that's the step where the 2+2.3GB partitions are created and made part of the raid1 sets, after that you can use remaining the space of the disk


as you are in VM for testing you can create dynamic disks with the 2 and 4 TB size an see the the numbers are as you expect them to be

if you want so see for yourself just boot up a iso with a live linux in your vm and use mdadm to assemble the raid1 of the dsm system partions on all disks


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