External USB-drive and F15

[Hiisi]

Hi, folks!
Recently I have been granted with external usb-drive. It's 3TB FA
GoFlex Desk of Seagate:
http://www.seagate.com/www/en-us/products/external/external-hard-drive/desktop-hard-drive/
I've formatted it as ext4 and plugged into machine running F 15. I use
it as apache server directory and as mysql data directory (this
computer serves as internal testing server for web-developers).
Everything works perfect except that I see a lot of errors in dmesg output:
[198659.222949] EXT4-fs error (device sdb1): ext4_find_entry:933:
inode #53477379: comm updatedb: reading directory lblock 0
[198659.222955] EXT4-fs (sdb1): previous I/O error to superblock detected
[198659.222958] EXT4-fs error (device sdb1): ext4_find_entry:933:
inode #53477379: comm updatedb: reading directory lblock 0
[198659.222963] EXT4-fs (sdb1): previous I/O error to superblock detected

and then this:

[199022.120335] EXT4-fs (sdd1): recovery complete
[199022.120916] EXT4-fs (sdd1): mounted filesystem with ordered data
mode. Opts: (null)
[199022.120926] SELinux: initialized (dev sdd1, type ext4), uses xattr
[199103.197445] EXT4-fs (sdb1): previous I/O error to superblock detected
[199103.197465] EXT4-fs error (device sdb1):
__ext4_get_inode_loc:4779: inode #125045501: block 500170959: comm
mysqld: unable to read itable block
[199835.118854] sd 8:0:0:0: [sdd]  Sense Key : Recovered Error
[current] [descriptor]
[199835.118859] Descriptor sense data with sense descriptors (in hex):
[199835.118861]         72 01 04 1d 00 00 00 0e 09 0c 00 00 00 00 ee 27
[199835.118866]         00 08 00 80 40 50
[199835.118869] sd 8:0:0:0: [sdd]  ASC=0x4 ASCQ=0x1d
[199835.185354] sd 8:0:0:0: [sdd]  Sense Key : Recovered Error
[current] [descriptor]
[199835.185368] Descriptor sense data with sense descriptors (in hex):
[199835.185373]         72 01 04 1d 00 00 00 0e 09 0c 00 00 00 00 00 00
[199835.185391]         00 4f 00 c2 40 50

What's wrong with it? Should I test it somehow? Is it broken and must
be replaced?
Another question here. Could anyone suggest how to prevent disk from
going into sleep mode? When it sits by weekends without work it stops
and after that it takes a few minutes to start it again. By the way, I
put following to /etc/fstab in order drive to be mounted during boot
process:
UUID=632ce2dc-97e5-47ed-9ddf-2217f136e637 /srv			  ext4	  defaults	  1 2

TIA
--
Hiisi