Linux – Which command to force a drive to spin up

USB drives have a chipset that converts USB mass-storage-device commands to IDE or SATA commands, which the drive then receives. Cheap chipsets (which are the majority, I imagine) don't pass on commands correctly to the drive that aren't directly related to reading or writing data from the drive. You are kind of at the mercy of that hardware with USB enclosures.

Sounds like only the most significant bit of the that -S value is being read by the drive or controller (off (>128) = power save mode, on (<127) = high performance mode)

You might get better feature support if your system has an eSATA port. eSATA talks directly to the drive so there is no "translation" or bridging of commands needed.

In my opinion, the best thing you can do to ensure a long life for a hard drive is:

• clean power to the system, get a power-conditioning UPS
• keep the device in a room with a steady ~70 degree temperature and low-humidity
• minimize powering them on and off, but do power them down if not being used for an extended period of time
• backups, backups, backups.

I'd say put your money into a UPS and another drive for backup. Do a RAID thing if you like.

After changing to backports kernel 3.2.0-0.bpo.3-amd64 there is no longer a wake of all drives between issuing reboot and message Will now restart. appears, with or without swap being enabled.

Note that the console "end_request I/O error, dev sdb, sector {0, 8, 16, 128, 4096}" error messages are still there when the drives are in standby state.

Update #1

The "Synchronizing SCSI cache before rebooting" issue re-appears in 3.2.0-0.bpo.4-amd64. Although both seem to share the same version of the mpt2sas module:

# modinfo /lib/modules/3.2.0-0.bpo.{3,4}-amd64/kernel/drivers/scsi/mpt2sas/mpt2sas.ko | grep ^version
version:        10.100.00.00
version:        10.100.00.00

Update #2

The issue doesn't seem to be kernel and storage module related. After changing back to kernel 2.6.32-5-amd64, setting all drives to standby, and commanding a reboot, there were no "Synchronizing SCSI cache", no drive spin ups, and therefore no delays.

Update #3

When turning off write cache hdparm -W0 /dev/sd? and flushing the write cache with sync && sdparm --command=sync /dev/sd? && sleep 1 and finally setting the drive to standby using hdparm -y /dev/sd? then there is no "Synchronizing SCSI cache" for every drive after running reboot and seeing output "Mounting root filesystem read-only...done." and "Will now restart." when using:

1. Linux debian 2.6.32-5-amd64 #1 SMP Sun Sep 23 10:07:46 UTC 2012 x86_64
2. Linux debian 3.2.0-0.bpo.3-amd64 #1 SMP Thu Aug 23 07:41:30 UTC 2012 x86_64

Kernel 3.2.0-0.bpo.4-amd64 is faulty and does "Synchronizing SCSI cache" for every drive on every reboot.