Now You have Current Pending Sector on the sda hard disk. This disk is used in software RAID. There is a start of death. You need to replace this disk.
This disk is designed for desktop PC. It tries to recovery itself (not via RAID). It reads bad sector every several seconds until checksum of bad sector will be good (disk's performance will drop dramatically), then the disk will write the read data to a new reserved sector. But the read data from rescued sector may be wrong often. CRC32 checksum can only indicate first error and it doesn't usable for recovering data (by example - XOR on RAID-5 can used for recovering data). When RAID will have read these data from the bad drive it will give different data, which will be read OK. This situation will produce kernel panic on the system if bad block has important system data. That is why You need to replace bad disk.