Hi Everyone,

Very new to Unraid (about 6 days in) but have been loving it so far. Its all worked pretty flawless and the docs have been very handy. However, I have run into problem which I cant seem to find a solution to. I recently

• Got two WD Red SSDs to use a cache pool

• Stopped the array

• Made a cache pool and assigned the drives

• Started the array

• Clicked Yes, I want to do this and then hit format for those drives.

This is where the issue begins. That format ran for a little bit but once it ended, in the cache pool is now said "Unmountable: wrong or no file system" and the drives showed back up next to the format option. I have tried that a couple times and it continues to be the same behavior.

Taking a look at the logs I see some lines that seems suspicious based on my basic linux/tech knowledge but I don't have enough Unraid/Disk management knowledge to say for sure or how to handle them

emhttpd: writing MBR on disk (sdc) with partition 1 offset 2048, erased: 0
emhttpd: shcmd (339): /usr/sbin/partprobe -s /dev/sdc
root: /dev/sdc: msdos partitions
emhttpd: shcmd (340): udevadm settle
emhttpd: /bin/lsblk -lnbo TYPE,NAME,START,SIZE /dev/sdc 2>&1
emhttpd: disk sdc  1000204886016
emhttpd: device sdc: no partitions
emhttpd: shcmd (341): /sbin/wipefs -af --lock /dev/
root: wipefs: error: /dev/: probing initialization failed: Is a directory
emhttpd: shcmd (341): exit status: 1
emhttpd: shcmd (342): /sbin/blkdiscard /dev/
root: blkdiscard: cannot open /dev/: Is a directory
emhttpd: shcmd (342): exit status: 1

I have also attached the full diagnostics zip. Thanks in advance for any help

kaldortower-diagnostics-20251010-1448.zip

Edited October 10, 2025Oct 10 by ArunawayNERD

Assuming the device IDs are still the same, type blkdiscard -f /dev/sdb and blkdiscard -f /dev/sdc, then reboot and try again, if it still fails please post new diags.

So those commands actually failed, but the error messages were enough to put me on the right track to figuring it out. Both the SSDs are now formatted and operating in the cache pool. Thank you so much for your help

For anyone else with the same issue who might come across this in the future here was my issue (/journey lol)

So both blkdiscard -f /dev/sdb and blkdiscard -f /dev/sdc failed with the same error message BLKDISCARD: /dev/sdb ioctl failed: Input/output error. At the end of system log (amongst a bunch of other error/logs) was the line device reported invalid CHS sector 0

When googling that error I was coming across a lot of posts about checking the sata cables, the connections, the sata ports, etc. That triggered in my mind that I had plugged these SSDs into sata port 4 and 5 on my motherboard. I also vaguely remember seeing some bios setting specifically for ports 4 and 5. Sure enough there was the setting "OnChip SATA Port 4/5 Type" which was defaulted to "IDE".

I switched it to "As SATA", saved, and exited. Once Unraid came up I tried formatting the drives again and it succeed

Thanks again for the help