Sata Disk очень низкая производительность

У меня HP MicroServer NL54, стандартный BIOS, с 4 жесткими дисками Seagate Barracuda ST2000DM001 2 ТБ, 7200 об / мин, 64 МБ кэш-памяти.

Если я проведу тест dd, я получу:

$ dd if = / dev / zero of = / dev / sdb bs = 4K count = 4096 4096 + 0 записей в 4096 + 0 записей из 16777216 байт (17 МБ) скопировано, 3,52959 с, 4,8 МБ / с

4.8, 4.9, 5 МБ / с макс.!

Вот мой dmesg:

[    3.019637] ata1: PATA max UDMA/100 cmd 0x1f0 ctl 0x3f6 bmdma 0xff00 irq 14
[    3.019681] ata2: PATA max UDMA/100 cmd 0x170 ctl 0x376 bmdma 0xff08 irq 15
[    3.022465] ata3: SATA max UDMA/133 abar m1024@0xfe5ffc00 port 0xfe5ffd00 irq 43
[    3.022509] ata4: SATA max UDMA/133 abar m1024@0xfe5ffc00 port 0xfe5ffd80 irq 43
[    3.022552] ata5: SATA max UDMA/133 abar m1024@0xfe5ffc00 port 0xfe5ffe00 irq 43
[    3.022594] ata6: SATA max UDMA/133 abar m1024@0xfe5ffc00 port 0xfe5ffe80 irq 43
[    3.516847] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    3.516926] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    3.516998] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    3.517056] ata6: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    3.517579] ata5.00: ATA-8: ST2000DM001-1E6164, SC48, max UDMA/133
[    3.517628] ata5.00: 3907029168 sectors, multi 0: LBA48 
[    3.517695] ata4.00: ATA-8: ST2000DM001-1E6164, SC48, max UDMA/133
[    3.517735] ata4.00: 3907029168 sectors, multi 0: LBA48 
[    3.518233] ata6.00: ATA-8: ST2000DM001-1CH164, CC24, max UDMA/133
[    3.518284] ata6.00: 3907029168 sectors, multi 0: LBA48 NCQ (depth 31/32), AA
[    3.518365] ata5.00: configured for UDMA/133
[    3.518474] ata4.00: configured for UDMA/133
[    3.519089] ata6.00: configured for UDMA/133
[    3.523456] ata3.00: ATA-7: SAMSUNG HD502HI, 1AG01118, max UDMA7
[    3.523502] ata3.00: 976773168 sectors, multi 0: LBA48 NCQ (depth 31/32), AA
[    3.530067] ata3.00: configured for UDMA/133
[    3.549678] sd 3:0:0:0: [sdb] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB)
[    3.549753] sd 3:0:0:0: [sdb] 4096-byte physical blocks
[    3.549813] sd 4:0:0:0: [sdc] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB)
[    3.549856] sd 4:0:0:0: [sdc] 4096-byte physical blocks
[    3.549860] sd 5:0:0:0: [sdd] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB)
[    3.549863] sd 5:0:0:0: [sdd] 4096-byte physical blocks
[    3.549943] sd 5:0:0:0: [sdd] Write Protect is off
[    3.549946] sd 5:0:0:0: [sdd] Mode Sense: 00 3a 00 00
[    3.549965] sd 5:0:0:0: [sdd] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.550092] sd 2:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB)
[    3.550194] sd 2:0:0:0: [sda] Write Protect is off
[    3.550235] sd 2:0:0:0: [sda] Mode Sense: 00 3a 00 00
[    3.550278] sd 2:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.550297] sd 3:0:0:0: [sdb] Write Protect is off
[    3.550300] sd 3:0:0:0: [sdb] Mode Sense: 00 3a 00 00
[    3.550319] sd 3:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.550531] sd 4:0:0:0: [sdc] Write Protect is off
[    3.550576] sd 4:0:0:0: [sdc] Mode Sense: 00 3a 00 00
[    3.550606] sd 4:0:0:0: [sdc] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.557986] sd 2:0:0:0: Attached scsi generic sg0 type 0
[    3.558127] sd 3:0:0:0: Attached scsi generic sg1 type 0
[    3.558335] sd 4:0:0:0: Attached scsi generic sg2 type 0
[    3.558468] sd 5:0:0:0: Attached scsi generic sg3 type 0
[    3.566284] sd 2:0:0:0: [sda] Attached SCSI disk
[    3.572387] sd 3:0:0:0: [sdb] Attached SCSI disk
[    3.583672] sd 4:0:0:0: [sdc] Attached SCSI disk
[    3.610449] sd 5:0:0:0: [sdd] Attached SCSI disk    

В BIOS он настроен как AHCI.

Есть предположения?