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My Disk writes too slow - why ?
#1
I am using and old 3 Gbp/s 64 bit Windows 7 Ultimate + SP1 on a Desktop with several OLD 3 Gbp/s Disks,
plus a NEW 6 Gbp/s Green 2000 GB drive from WDC which writes at less than half the speed of the 3 Gbp/s Disks.

This 6 Gbp/s 2000 GB has a 100 GB partition at the beginning
and can read at the same 146 MB/s as the fast end of the Samsung
but only write at 68 MB/s - 48% of the read speed.
That is 11% of the 600 MB/s that SATA 3 should handle.
-----------------------------------------------------------------------
CrystalDiskMark 3.0.3 x64 © 2007-2013 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 146.163 MB/s
Sequential Write : 68.089 MB/s
Random Read 512KB : 49.389 MB/s
Random Write 512KB : 62.036 MB/s
Random Read 4KB (QD=1) : 0.592 MB/s [ 144.4 IOPS]
Random Write 4KB (QD=1) : 1.916 MB/s [ 467.8 IOPS]
Random Read 4KB (QD=32) : 0.667 MB/s [ 162.7 IOPS]
Random Write 4KB (QD=32) : 1.978 MB/s [ 483.0 IOPS]
Test : 500 MB [V: 2.5% (2.4/97.7 GB)] (x1)
Date : 2014/06/16 11:14:22
OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)
500 MB test on V: (2 TB Disk - slow write)

Should I alter the SATA connections for a different interface ?


An old Samsung 3 Gbp/s 960 GB Disc reads and writes at more than 142 MB/s at the start end. exceeds 78 MB/s at the other end.
-----------------------------------------------------------------------
CrystalDiskMark 3.0.3 x64 © 2007-2013 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 146.942 MB/s
Sequential Write : 142.644 MB/s
Random Read 512KB : 44.533 MB/s
Random Write 512KB : 63.253 MB/s
Random Read 4KB (QD=1) : 0.538 MB/s [ 131.2 IOPS]
Random Write 4KB (QD=1) : 1.289 MB/s [ 314.7 IOPS]
Random Read 4KB (QD=32) : 1.147 MB/s [ 280.0 IOPS]
Random Write 4KB (QD=32) : 1.226 MB/s [ 299.2 IOPS]
Test : 500 MB [F: 77.8% (19.4/25.0 GB)] (x1)
Date : 2014/06/16 11:09:09
OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)
500 MB test on F:

An old Samsung 3 Gbp/s 960 GB Disc reads and writes at exceeds 78 MB/s at the slow end.
-----------------------------------------------------------------------
CrystalDiskMark 3.0.3 x64 © 2007-2013 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 78.864 MB/s
Sequential Write : 77.707 MB/s
Random Read 512KB : 35.064 MB/s
Random Write 512KB : 45.030 MB/s
Random Read 4KB (QD=1) : 0.490 MB/s [ 119.7 IOPS]
Random Write 4KB (QD=1) : 1.073 MB/s [ 262.0 IOPS]
Random Read 4KB (QD=32) : 0.954 MB/s [ 233.0 IOPS]
Random Write 4KB (QD=32) : 1.061 MB/s [ 259.1 IOPS]
Test : 500 MB [I: 79.3% (77.5/97.7 GB)] (x1)
Date : 2014/06/16 11:01:30
OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)
500 MB test on I:

I do not care about the NEW Disk read speed,
but the write speed is horribly inconvenient.
This disk is will often receive the writing of new backup files and that must happen quickly.
Only rarely would I need to read a backup file.

I am seriously thinking of throwing this Disk back at Amazon as being deceitfully marketed.
It was a 3.5 inch drive so I was surprised to find it runs at 2.5 inch speed of 5400 r.p.m.
I was hoping that if/when I upgrade to a new system with SATA 3 capability then this disk would be ready for the benefit.

What is the purpose of a 6 Gbps speed interface on something that writes at less than half the speed of a 3 Gbps interface.
That seems like gold-plating doggy excrement - it does not make it more acceptable in the house Angry

Regards
Alan


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#2
SATA interface speed does hardly offer any performance advantage as long as the disk is not capable to deliver high transfer rates.
Your WDC drive seems to be 5400 RPM only, so this can have a major impact on performance.
Also, all your drives (including the WDC) seem to be running at 3 Gbps only. This could be because of the connection, but anyway, I doubt that running this drive at higher SATA interface speeds will cause significant performance gain.
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#3
(06-16-2014, 01:42 PM)Martin Wrote: Your WDC drive seems to be 5400 RPM only, so this can have a major impact on performance.
This 2 TB Disk has the same speed as the 960 TB Disk when Reading
Why can the 5400 r.p.m drive keep up with the older smaller 7200 rpm drive when READING,
BUT chug along at less than half speed when WRITING.
This suggests that the same number of bytes will be read by the heads of the drive in one second as will be written in one second by the 7200 drive,
but need TWO seconds for writing that number of bytes to the 5400 drive.

I remember formatting Floppy Diskettes with DOS 3.3?
and inter-sector gaps and interleave factors could mean that consecutively numbers sectors were NOT adjacent,
and to read or write a long file using ALL the sectors on a disk would require 2 or more rotations.

Have WDC made a terrible mistake with their so-called "Advanced Format",
and although they recover from reading sector 2 in time to read sector 3,
they recover from Writing sector 2 just after sector 3 has gone by so that has to wait an extra rotation ?

Regards
Alan
Reply
#4
(06-16-2014, 01:29 PM)alan9182 Wrote: I am using and old 3 Gbp/s 64 bit Windows 7 Ultimate + SP1 on a Desktop with several OLD 3 Gbp/s Disks,
plus a NEW 6 Gbp/s Green 2000 GB drive from WDC which writes at less than half the speed of the 3 Gbp/s Disks.

This 6 Gbp/s 2000 GB has a 100 GB partition at the beginning
and can read at the same 146 MB/s as the fast end of the Samsung
but only write at 68 MB/s - 48% of the read speed.
That is 11% of the 600 MB/s that SATA 3 should handle.
...
What is the purpose of a 6 Gbps speed interface on something that writes at less than half the speed of a 3 Gbps interface.
That seems like gold-plating doggy excrement - it does not make it more acceptable in the house Angry

Regards
Alan

First we would need to know what model mother board you are using, to determine the type(s) and speed of the SATA interface(s) it has. Do you know that your board has some SATA III ports available?

Next but really most important, there are exactly zero HDDs of any kind that can fully use the speed that even SATA II provides, despite some of those HDDs being labeled "SATA III". At best the input buffer (possibly 64MB of RAM) of the HDD can accept data at SATA III speeds (real world max sequential read and write, ~540MB/s) but that data is still written to the HDD at whatever its limit is. The reality is, the majority of HDDs can barely exceed SATA I speeds, even simply reading large sequential files. The small file random read speeds are even more pathetic.

Your new disk likely has higher data density, more bits are written on less space than your older HDD, which allows it to read data at the same rate as your old HDD. That's basically how all the high capacity HDDs work, more data per platter. Reading is also easier to do that writing, and when the new disk must write at 5400 RPM more precisely due to the higher data density, it takes longer.

Having the SATA mode set to AHCI helps a bit to speed up HDD speeds. Using the new HDD on a SATA III port will make no difference, its speed will be identical to a SATA II port.

I don't understand how HDD manufactures can market the drives as SATA III, simply because the IO buffer can accept bursts of data at higher speeds, if that is truly the caveat or fine print. Any HDD with an input buffer could qualify.
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