Please replace the /dev/sda disk on mw1230, as SMART is reporting it as failed.
mw1230:~# smartctl -H /dev/sda === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: FAILED! Drive failure expected in less than 24 hours. SAVE ALL DATA. Failed Attributes: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 001 001 051 Pre-fail Always FAILING_NOW 8127
I will depool the server, you can then just power it off, swap the disk with a new one, and start it again. The raid will rebiuld itself.