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SATA drive seems slow... (hdparm -Tt /dev/sda)
http://forum.linhes.org/viewtopic.php?f=2&t=19099		 Page 1 of 1
Author:  graysky [ Mon Oct 13, 2008 2:10 am ]
Post subject:  SATA drive seems slow... (hdparm -Tt /dev/sda)
My SATA drive seems awfully slow for the hardware specs of this Debian-Lenny system. Can you guys post the output of your hdparm -Tt commands with your hardware specs for me as well as provide any comments/suggestions?

Thanks!

Hardware specs: A7N8X-E Deluxe, Athlon XP 3200+, 2x512 meg DDR2-400, HDD is a Hitachi HDS722516VLSA80 150 GB SATA1 drive using the kernel's Silicon Image, Inc. SiI 3112 driver.

Code:
# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   1092 MB in  2.00 seconds = 546.06 MB/sec
 Timing buffered disk reads:  176 MB in  3.02 seconds = 58.27 MB/sec


By contrast, here is the hdparm -Tt for my really old, 80 gig Western Digital WD800 UDMA-100 drive:

Code:
# hdparm -Tt /dev/hda

/dev/hda:
Timing cached reads: 1142 MB in 2.00 seconds = 570.72 MB/sec
Timing buffered disk reads: 140 MB in 3.01 seconds = 46.48 MB/sec


Here is the output of sdparm:

Code:
# sdparm /dev/sda
    /dev/sda: ATA       HDS722516VLSA80   V34O
Read write error recovery mode page:
  AWRE        1
  ARRE        1
  PER         0
Caching (SBC) mode page:
  WCE         1
  RCD         0
Control mode page:
  SWP         0
Author:  alien [ Tue Oct 14, 2008 2:09 am ]
Post subject: 
I get similar results (same MB):

Code:
/dev/sda:
 Timing cached reads:   752 MB in  2.00 seconds = 375.35 MB/sec
 Timing buffered disk reads:  224 MB in  3.01 seconds =  74.38 MB/sec
root@violet:~# hdparm -Tt /dev/hda

/dev/hda:
 Timing cached reads:   742 MB in  2.00 seconds = 370.77 MB/sec
 Timing buffered disk reads:  160 MB in  3.02 seconds =  52.94 MB/sec
root@violet:~#


There are a couple of reasons for this:

1. Most HDs are limited by their read/write speed. Not the cable speed.

2. The A7N8X-E Deluxe has an older SATA/150 which performs similarly to a PATA/133 in many cases.

Lot's more information here:

http://en.wikipedia.org/wiki/Sata#Throughput
Author:  opel70 [ Tue Oct 14, 2008 8:46 am ]
Post subject: 
My system shows up with:
Code:
/dev/sdb
 Timing cached reads:   2060 MB in  2.00 seconds = 1030.04 MB/sec
 Timing buffered disk reads:  212 MB in  3.01 seconds =  70.66 MB/sec

This is on a Seagate Baracuda 750GB drive. The sdparm output is the same.
Author:  manicmike [ Tue Oct 14, 2008 2:11 pm ]
Post subject: 
That's an interesting set of numbers. I hadn't used hdparm for years, but this is what it said about my WD 5000YS
Code:
/dev/sda:
 Timing cached reads:   5752 MB in  1.99 seconds = 2885.60 MB/sec
 Timing buffered disk reads:  212 MB in  3.02 seconds =  70.24 MB/sec


Very cool: Didn't realise drives were that different in r/w speed.

Mike
Author:  Dale [ Tue Oct 14, 2008 3:26 pm ]
Post subject: 
If you said what type fs you have on the partition, I missed it. I have just recently timed some xfs stuff here, and have discovered that on a new xfs partition it was really slow compared to a new ext3 fs on the same partiition. I'm sticking with ext3 from now on.
Author:  alien [ Wed Oct 15, 2008 1:21 am ]
Post subject: 
The first number, "Timing cached reads" is a measure of the CPU, cache and memory. I.e. Everything except the HD. The second number is a measure of the HD speed. Surprising similar in all cases..... Except for graysky, but his drive appears to be an older generation (150G Sata1).

Dale,

Did you find a difference in the hdparm timings with different partition formats? That seems strange because hdparm doesn't take a partition as a parameter. I didn't think it measured the fs performance (what would it do with two partitions with different formats?).
Author:  marc.aronson [ Wed Oct 15, 2008 2:23 am ]
Post subject: 
Timings for Western Digital 750GB SATA green drive:
Code:
/dev/sda:
 Timing cached reads:   14070 MB in  1.99 seconds = 7053.55 MB/sec
 Timing buffered disk reads:  230 MB in  3.00 seconds =  76.63 MB/sec
root@mythhd:~# hdparm -Tt /dev/hda


Timings for Seagate 400GB IDE drive:
Code:
/dev/hda:
 Timing cached reads:   13826 MB in  2.00 seconds = 6930.18 MB/sec
 Timing buffered disk reads:  200 MB in  3.00 seconds =  66.62 MB/sec
Author:  manicmike [ Wed Oct 15, 2008 5:54 am ]
Post subject: 
Just so you know, the hdparm man page says that the numbers are meaningless if you don't perform the operation 2 or 3 times, the last one being most accurate.

Mine were all pretty close, though. WD5000YS
Code:
/dev/sda3:
 Timing cached reads:   5670 MB in  1.99 seconds = 2844.32 MB/sec
 Timing buffered disk reads:  212 MB in  3.03 seconds =  70.07 MB/sec


I think the idea behind the 2-3 times is to wake the disk up. Numbers were substantialy different for another drive that doesn't get used much.

Mike.
Author:  Dale [ Wed Oct 15, 2008 10:55 am ]
Post subject: 
alien wrote:
Did you find a difference in the hdparm timings with different partition formats? That seems strange because hdparm doesn't take a partition as a parameter. I didn't think it measured the fs performance (what would it do with two partitions with different formats?).


Actually, I did not use hdparm on the partitions, I timed some actual work taking place on fresh new filesystems.
Author:  graysky [ Sat Jan 03, 2009 1:37 pm ]
Post subject: 
An update, I think the numbers I was getting are just fine given the vintage of the hardware (SATA1). I ran the same on my P35-based/SATAII system and got the following under Ubuntu 8.10:

Code:
$ sudo hdparm -Tt /dev/sda1

/dev/sda1:
 Timing cached reads:   15880 MB in  2.00 seconds = 7952.77 MB/sec
 Timing buffered disk reads:  344 MB in  3.01 seconds = 114.19 MB/sec
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