sector hard errors

[jd1008]

Hi all,
on a new drive, installed about 3 months ago ... fsck shows:



Pass 5: Checking group summary information
[  117.650425] ata5.00: exception Emask 0x0 SAct 0xc0 SErr 0x0 action 0x0
[  117.650678] ata5.00: irq_stat 0x40000008
[  117.650840] ata5.00: failed command: READ FPDMA QUEUED
[  117.651523] ata5.00: cmd 60/80:30:68:08:40/00:00:be:00:00/40 tag 6 
ncq 65536 in
[  117.651523]          res 41/40:00:b0:08:40/00:00:be:00:00/40 Emask 
0x409 (media error) <F>
[  117.652872] ata5.00: status: { DRDY ERR }
[  117.653547] ata5.00: error: { UNC }
[  117.655604] ata5.00: configured for UDMA/133
[  117.655825] sd 4:0:0:0: [sdb]
[  117.655991] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[  117.656631] sd 4:0:0:0: [sdb]
[  117.657288] Sense Key : Medium Error [current] [descriptor]
[  117.657966] Descriptor sense data with sense descriptors (in hex):
[  117.658652]         72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
[  117.659381]         be 40 08 b0
[  117.660065] sd 4:0:0:0: [sdb]
[  117.660703] Add. Sense: Unrecovered read error - auto reallocate failed
[  117.661349] sd 4:0:0:0: [sdb] CDB:
[  117.661981] Read(10): 28 00 be 40 08 68 00 00 80 00
[  117.662667] blk_update_request: I/O error, dev sdb, sector 3191867568
[  117.663323] ata5: EH complete
[  129.095402] ata5.00: exception Emask 0x0 SAct 0x3000000 SErr 0x0 
action 0x0
[  129.095663] ata5.00: irq_stat 0x40000008
[  129.095826] ata5.00: failed command: READ FPDMA QUEUED
[  129.096434] ata5.00: cmd 60/00:c0:e8:08:00/01:00:c2:00:00/40 tag 24 
ncq 131072 in
[  129.096434]          res 41/40:00:90:09:00/00:00:c2:00:00/40 Emask 
0x409 (media error) <F>
[  129.097727] ata5.00: status: { DRDY ERR }
[  129.098393] ata5.00: error: { UNC }
[  129.100528] ata5.00: configured for UDMA/133
[  129.100768] sd 4:0:0:0: [sdb]
[  129.100935] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[  129.101530] sd 4:0:0:0: [sdb]
[  129.102128] Sense Key : Medium Error [current] [descriptor]
[  129.102728] Descriptor sense data with sense descriptors (in hex):
[  129.103349]         72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
[  129.103998]         c2 00 09 90
[  129.104645] sd 4:0:0:0: [sdb]
[  129.105280] Add. Sense: Unrecovered read error - auto reallocate failed
[  129.105911] sd 4:0:0:0: [sdb] CDB:
[  129.106567] Read(10): 28 00 c2 00 08 e8 00 01 00 00
[  129.107271] blk_update_request: I/O error, dev sdb, sector 3254782352
[  129.107954] ata5: EH complete

So, I am puzzled as to how quickly were the spare sectors consumed so that
automatic sector forwarding ran out os spare sectors? So quickly on a
brand new drive??
When someone buys a brand new drive, how many spare sectors is it guaranteed
to have? ZERO? ONE??  How many?