Partition table not recognized by Linux kernel

For some reason your kernel fails to read the partition table:

[ 8775.030291] end_request: I/O error, dev sdb, sector 0
[ 8775.030300] quiet_error: 30 callbacks suppressed
[ 8775.030306] Buffer I/O error on device sdb, logical block 0
[ 8775.033781] ldm_validate_partition_table(): Disk read failed.

Thus, it can't create devices for partitions as it did not read the partition table. Later when you try to see the partition table with parted or fdisk the IO is performed successfully.

Try to use partprobe /dev/sdX when your kernel did not recognized the partitions at boot time.

man partprobe:

PARTPROBE(8)                                                         GNU Parted Manual                                                        PARTPROBE(8)

NAME
       partprobe - inform the OS of partition table changes

SYNOPSIS
       partprobe [-d] [-s] [devices...]

DESCRIPTION
       This manual page documents briefly the partprobe command.

       partprobe  is  a  program  that informs the operating system kernel of partition table changes, by requesting that the operating system re-read the
       partition table.