Hard Drive data rates

[Karl Larsen]

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.
>>>     
>>
>> Karl,
>>
>> 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 at k5di /]# hdparm -iItT
>
> hdparm - get/set hard disk parameters - version v6.9
>
> Usage:  hdparm  [options] [device] ..
>
> Options:
> -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 at k5di /]# hdparm -tT /dev/sda

/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 at k5di /]# hdparm -tT /dev/sdf

/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 at 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.