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Re: [opensuse] Real World Sata-II disk-to-disk throughput? 77MB/sec is that about right?
On 9/25/2011 4:53 PM, David C. Rankin wrote:
Guys,

Copying video between two Seagate ST31500341AS disks with ext3
filesystems I get about 77.8 MB/sec. Given they are supposed to be 300
MB/sec:

"Is the 77 MB/sec close to the real world max I should expect?"

I understand that the 300 MB/sec is the 'theoretical max' throughput,
but I have never really thought about what the 'real-world max' should
be. I know there are various factors from hardware to number and size of
files that impact the rate, but I'm just trying to get an idea if this
is reasonable.

The transfer was conducted using about 13 GB (about 1 hr. of video) of
data in about 25 files:

15:37 archangel:/dat_e/dv> du -hcs sony/dcrv-1999.0[45].[023][167890]_*
1001M sony/dcrv-1999.04.26_08-29-00.dv
1.5M sony/dcrv-1999.04.26_09-46-11.dv
230M sony/dcrv-1999.04.26_11-24-21.dv
163M sony/dcrv-1999.04.26_12-47-59.dv
1001M sony/dcrv-1999.04.26_15-41-40.dv
1001M sony/dcrv-1999.04.26_15-58-20.dv
362M sony/dcrv-1999.04.26_16-33-49.dv
404M sony/dcrv-1999.04.26_17-50-38.dv
335M sony/dcrv-1999.04.27_02-37-23.dv
331M sony/dcrv-1999.04.27_09-17-43.dv
838M sony/dcrv-1999.04.27_11-15-13.dv
264M sony/dcrv-1999.04.27_14-07-24.dv
229M sony/dcrv-1999.04.27_20-10-51.dv
140M sony/dcrv-1999.04.28_07-36-11.dv
462M sony/dcrv-1999.04.28_08-41-43.dv
1001M sony/dcrv-1999.04.28_10-52-18.dv
584M sony/dcrv-1999.04.28_11-07-26.dv
373M sony/dcrv-1999.04.28_14-50-35.dv
1001M sony/dcrv-1999.04.28_19-47-44.dv
159M sony/dcrv-1999.04.28_20-07-08.dv
206M sony/dcrv-1999.04.29_14-38-06.dv
1001M sony/dcrv-1999.04.29_20-56-26.dv
431M sony/dcrv-1999.04.29_21-18-38.dv
258M sony/dcrv-1999.04.30_22-33-44.dv
546M sony/dcrv-1999.05.01_17-14-07.dv
13G total

The timing of the transfer was:

15:37 archangel:/dat_e/dv> time cp -uav /dat_e/dv/{sony,tape-idx.txt}
/dat_f/dv/
`/dat_e/dv/sony/dcrv-1999.04.29_21-18-38.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.29_21-18-38.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_14-50-35.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_14-50-35.dv'
`/dat_e/dv/sony/dcrv-1999.04.29_14-38-06.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.29_14-38-06.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_10-52-18.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_10-52-18.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_15-41-40.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_15-41-40.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_20-07-08.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_20-07-08.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_07-36-11.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_07-36-11.dv'
`/dat_e/dv/sony/dcrv-1999.04.27_11-15-13.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.27_11-15-13.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_15-58-20.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_15-58-20.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_12-47-59.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_12-47-59.dv'
`/dat_e/dv/sony/dcrv-1999.04.27_09-17-43.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.27_09-17-43.dv'
`/dat_e/dv/sony/dcrv-1999.04.29_20-56-26.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.29_20-56-26.dv'
`/dat_e/dv/sony/dcrv-1999.05.01_17-14-07.dv' ->
`/dat_f/dv/sony/dcrv-1999.05.01_17-14-07.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_19-47-44.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_19-47-44.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_11-07-26.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_11-07-26.dv'
`/dat_e/dv/sony/dcrv-1999.04.27_20-10-51.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.27_20-10-51.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_17-50-38.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_17-50-38.dv'
`/dat_e/dv/sony/dcrv-1999.04.28_08-41-43.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.28_08-41-43.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_11-24-21.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_11-24-21.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_16-33-49.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_16-33-49.dv'
`/dat_e/dv/sony/dcrv-1999.04.27_02-37-23.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.27_02-37-23.dv'
`/dat_e/dv/sony/dcrv-1999.04.27_14-07-24.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.27_14-07-24.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_09-46-11.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_09-46-11.dv'
`/dat_e/dv/sony/dcrv-1999.04.26_08-29-00.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.26_08-29-00.dv'
`/dat_e/dv/sony/dcrv-1999.04.30_22-33-44.dv' ->
`/dat_f/dv/sony/dcrv-1999.04.30_22-33-44.dv'

real 2m47.980s
user 0m0.083s
sys 0m27.982s

What say the experts - reasonable throughput?


3Gb is just the interface, only the cache on a single drive can even approach that speed. The disk itself even under the ideal theoretical conditions of sequential sustained read from the outer edge of the platters on a high end 15krpm disk and doing a raw read not going through any filesystem overhead, can only reach about 90MB.

77 reading files (not raw data) from one filesystem and writing to files on another filesystem, might not be the absolute highest these drives could attain, there might be some areas of your total system that could be tweaked a little, but it is quite good.

To go more than a tiny bit faster you need ssd's or raid.

--
bkw
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