ReadyNAS 4220X

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kalanfuga wrote:
However, I'm learning that this thing is very limited, in that the OS all sits on 256MB of flash on the mobo. I've dug around and can't seem to find any real technical information on the motherboard. 

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Not exactly the case.  The flash contains a compressed image of the un-initialized OS as well as a very small image that can be put in RAM for troubleshooting and a syslinux boot that chroot's to the main OS on boot (unless you use the reset button menu and tell it to do otherwise).  The working OS is installed in a RAID1 across all installed drives, as is the swap partition.  The OS partition is 4GB and swap is 512MB.  That's still a bit small for a Linux OS partition, but it's plenty for most who mainly just use the NAS for storage.  The flash is not accessed (or even accessible) during normal operation, nor is any user data put there.

The chassis is manufactured by Chenbro, and I suspect the motherboard is as well, but to a Netgear design (there is definitely no Chenbro equivalent, but it's design in Chenbro-ish).  So, you can use power supplies, fans, and caddies intended for Chenbro if you need replacements.  The only real limitation of the motherboard is no video port and only one expansion slot.  So, if you need video, you have no space for anything else.  The 10GBE daughterboard is also proprietary, as far as I have been able to determine, so you'd have to use the expansion slot (and thus give up video) if you don't like the connector type.

Now, since Netgear has clearly abandoned the ReadyNAS line and the current OS is way out of date, you may still wish to put a different OS on it now instead of jumping on ReadyNAS OS so close to it's presumed demise.