Seguimos con el ahorro: El disco duro

Para activar el ahorro de energia en el disco necesitamos hdparm:
make
make binprefix=/usr/local/ manprefix=/usr/local/ install

Probemos hdparm -I /dev/hda

/dev/hda:

ATA device, with non-removable media
Model Number: FUJITSU MHV2040AT
Serial Number: NS9CT5925NAG
Firmware Revision: 00000096
Standards:
Used: ATA/ATAPI-6 T13 1410D revision 3a
Supported: 6 5 4
Configuration:
Logical max current
cylinders 16383 16383
heads 16 16
sectors/track 63 63
--
CHS current addressable sectors: 16514064
LBA user addressable sectors: 78140160
device size with M = 1024*1024: 38154 MBytes
device size with M = 1000*1000: 40007 MBytes (40 GB)

Capabilities:
LBA, IORDY(cannot be disabled)
Standby timer values: spec'd by Standard, no device specific minimum
R/W multiple sector transfer: Max = 16 Current = ?
Advanced power management level: 128 (0x80)
Recommended acoustic management value: 254, current value: 254
DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=240ns IORDY flow control=120ns
Commands/features:
Enabled Supported:
* SMART feature set
Security Mode feature set
* Power Management feature set
* Write cache
* Look-ahead
* Host Protected Area feature set
* WRITE_BUFFER command
* READ_BUFFER command
* DOWNLOAD_MICROCODE
* Advanced Power Management feature set
Power-Up In Standby feature set
* SET_MAX security extension
* Automatic Acoustic Management feature set
* Device Configuration Overlay feature set
* Mandatory FLUSH_CACHE
* SMART error logging
* SMART self-test
* IDLE_IMMEDIATE with UNLOAD
* SMART Command Transport (SCT) feature set
* SCT LBA Segment Access (AC2)
* SCT Error Recovery Control (AC3)
* SCT Features Control (AC4)
* SCT Data Tables (AC5)
Security:
Master password revision code = 65534
supported
not enabled
not locked
frozen
not expired: security count
not supported: enhanced erase
40min for SECURITY ERASE UNIT.
HW reset results:
CBLID- above Vih
Device num = 0 determined by the jumper
Checksum: correct

Y ahora hdparm -Tt /dev/hda

/dev/hda:
Timing cached reads: 1412 MB in 2.00 seconds = 706.00 MB/sec
Timing buffered disk reads: 80 MB in 3.02 seconds = 26.53 MB/sec

Aplicamos hdparm -d1 -c3 -m16 -M128 /dev/hda

Volvemos hacer hdparm -Tt /dev/hda
Timing cached reads: 1484 MB in 2.00 seconds = 741.98 MB/sec
Timing buffered disk reads: 80 MB in 3.01 seconds = 26.56 MB/sec

Realmente no se nota el cambio. Pero el hdparm nos sistema para suspender el disco duro con la opción -Sn, donde n * 5 de segundos de inactividad para suspender el disco.