Linda Walsh wrote:
Alan Cox wrote:
rate began falling; at 128k block-reads-at-a-time or larger, it drops
below
20MB/s (only on buffered SATA).
Try disabling NCQ - see if you've got a drive with the 'NCQ = no
readahead' flaw.
---
I'm not aware, off hand, how to disable NCQ. I haven't had any
NCQ- or SATA- capable disks before a few weeks ago.
See here:
http://linux-ata.org/faq.html#ncq
The only way I could tell before was using hdparm to read the
parameters. Since that doesn't work, it's hard to tell if they
are set correctly...
hdparm supports identify to read modes on drives with libata. The one
thing you cannot do is force modes right now.
More importantly, how does one set parameters for acoustic and power
saving parameters? Some of my disks are used as 'backup' devices for my
hdparm or blktool
----
I have hdparm-v7.7. There are some areas where it shows information,
but areas where it
does not work jump out and lead me to suspect whether or not areas
that don't give explicit "ERROR" messages are presenting valid info.
Problem areas (using hdparm, disk=Seagate Barracuda 16MB cache, model=
ST3750640AS):
1) The drives current 'multicount' setting isn't readable or settable.
param "-i" shows "?16?" (with question marks around 16) and "-I" simply
shows "?" for the current setting. Attempting to <read|set> it:
"HDIO_<GET|SET>_MULTCOUNT failed: Inappropriate ioctl for device"
I don't think you can get or get the multi count currently, it just uses
the best supported value.
2) Drive Advanced Power Management setting("-B") (write-only):
"HDIO_DRIVE_CMD failed: Input/output error"
3) Drive Acoustic ("-M"), read = " acoustic = not supported",
write = " HDIO_DRIVE_CMD:ACOUSTIC failed: Input/output error"
Note: drive detailed info from "-I" says:
"Recommended acoustic management value: 254, current value: 0"
(i.e. - there seems to be no way to set recommended value)
Not sure about these ones.. Does anything show up in dmesg when you do this?
4) 32-bit IO setting ("-c") (don't know if this important given the disk's
raw-read speed, it may be meaningless for SATA)
"IO_support = 0 (default 16-bit)"*
*
This setting is not meaningful for anything using DMA.
FWIW -- the spindown/standby timeout ("S") does seem to work.
other computers. With the ATA disks, they were kept "spun down" when
not
being used (only used, 'normally', in early AM hours).
Well for backup devices you can use the fact SATA is hot/warm plug.
---
I don't follow. It is an internal drive. Are their software "logically
unplug" commands that automatically re-"plug-in" the drive on access
and spin it back up like the spindown/standby timeout does? Or were
you referring to SATA's general hot/warm plug ability (if my hardware
setup, drive-slots, etc, permitted removability)?
I think they were referring to physically hotplugging the drive. This is
more practical if you have a removable drive caddy, or if the drive is
hooked up through eSATA.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page: http://www.roberthancock.com/
-
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
