Hard Drive data rates
Karl Larsen
k5di at zianet.com
Fri Sep 28 22:18:28 UTC 2007
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.
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