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Re: Hard Drive data rates

Karl Larsen wrote:
Dave Stevens wrote:
On Friday 28 September 2007 10:50:32 am Karl Larsen wrote:
    I was lead to mis-understand the data rate of my new SATA hard
drive. It indicated that the data rate was 3 GB/sec. But some checking
with Google said the Hard Drive makers are very free with their units.
To be specific a SATA drive is 3000 MegaBits/second. This boils down to
about 375 MB.

The old standard IDE parallel 40 pin plug is rated for a rate of 112
MB at the fastest to 78 GB at the slowest part of the platter. So in my
case I will not see a huge change moving to my SATA hard drive. I will
stay here on the new IDE much longer.

I'd be very interested in seeing the command and output for that drive using hdparm -iItT


    Karl F. Larsen, AKA K5DI
    Linux User
    #450462   http://counter.li.org.


I use a Seagate 320 gig ES SATA drive. This is a 3 Gb/sec drive BUT - it was shipped with a jumper installed limiting it to half that rate, and this rate is in any case a very optimistic one. Using hdparm as suggested consistently gives me 78 MB/sec. That seems to be as good as it gets. Also this is a very artificial figure, I have an old (about ten years) 9 gig SCSI drive that does about half that. It seems that the recent addition of NCQ to SATA drives makes more of an improvement in heavily loaded scenarios but quantifying this is not simple or unambiguous. I want to try reconfiguring this setup in raid 0 but won't be able to do so for a while. I know that another recent Seagate drive, their 400G ATA gives transfer rates using hdparm -tT of about 50 MB/sec.

There appears to be something wrong with hdparm on my computer. It only does this with all the various -tT and such:

[root k5di /]# hdparm -iItT

hdparm - get/set hard disk parameters - version v6.9

Usage:  hdparm  [options] [device] ..

-a   get/set fs readahead
-A   set drive read-lookahead flag (0/1)
-b   get/set bus state (0 == off, 1 == on, 2 == tristate)
-B   set Advanced Power Management setting (1-255)
-c   get/set IDE 32-bit IO setting
-C   check IDE power mode status
-d   get/set using_dma flag
--direct  use O_DIRECT to bypass page cache for timings
-D   enable/disable drive defect management
-E   set cd-rom drive speed
-f   flush buffer cache for device on exit
-g   display drive geometry
-h   display terse usage information
-H   read temperature from drive (Hitachi only)
-i   display drive identification
-I   detailed/current information directly from drive
--Istdin  read identify data from stdin as ASCII hex
--Istdout write identify data to stdout as ASCII hex
-k   get/set keep_settings_over_reset flag (0/1)
-K   set drive keep_features_over_reset flag (0/1)
-L   set drive doorlock (0/1) (removable harddisks only)
-M get/set acoustic management (0-254, 128: quiet, 254: fast) (EXPERIMENTAL)
-m   get/set multiple sector count
-n   get/set ignore-write-errors flag (0/1)
-p   set PIO mode on IDE interface chipset (0,1,2,3,4,...)
-P   set drive prefetch count
-q   change next setting quietly
-Q   get/set DMA tagged-queuing depth (if supported)
-r   get/set device  readonly flag (DANGEROUS to set)
-R   register an IDE interface (DANGEROUS)
-s   set power-up in standby flag (0/1)
-S   set standby (spindown) timeout
-t   perform device read timings
-T   perform cache read timings
-u   get/set unmaskirq flag (0/1)
-U   un-register an IDE interface (DANGEROUS)
-v   defaults; same as -mcudkrag for IDE drives
-V   display program version and exit immediately
-w   perform device reset (DANGEROUS)
-W   set drive write-caching flag (0/1) (DANGEROUS)
-x   tristate device for hotswap (0/1) (DANGEROUS)
-X   set IDE xfer mode (DANGEROUS)
-y   put IDE drive in standby mode
-Y   put IDE drive to sleep
-Z   disable Seagate auto-powersaving mode
-z   re-read partition table
--security-help  display help for ATA security commands

   So I can't use this for some reason.

But in reading man hdparm I discovered you all are misleading me. The actual thing to do is this:

# hdparm -tT /dev/sda

I did this for both this HD and then the SATA HD. Here is the results.

[root k5di /]# hdparm -tT /dev/sda

Timing cached reads:   1010 MB in  2.00 seconds = 504.77 MB/sec
Timing buffered disk reads:  122 MB in  3.03 seconds =  40.29 MB/sec
[root k5di /]# hdparm -tT /dev/sdf

Timing cached reads:   990 MB in  2.00 seconds = 494.77 MB/sec
Timing buffered disk reads:  146 MB in  3.01 seconds =  48.53 MB/sec
[root k5di /]#

sda is the IDE and sdf is the SATA. I know the SATA is not set to work as an IDE.


	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.

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