Slow disk I/O - was Re: Seeking Help

[geoff at thebakershome.net]

I should also point out that I get good speeds from hdparm on 12.10, just
certain tasks are slow. ie. apt-get update "Reading package lists",
transferring many files between drives (ie pictures), or compiling (cpu
does not work for long periods of time while files are accessed).

I do not know the best way to test this stuff using a live disk. The best
I can do is show that apt-get update completed in less than a minute on
the live disk, while on my installed disk (even with one one source
enabled), takes 20 minutes. This just shows that the network has nothing
to do with the main problem.

I see many differences in the names of what is detected for the chipset,
but not much for actual functions.

12.10 pastebin: http://pastebin.ubuntu.com/1561660/

12.04 live pastebin: http://paste.ubuntu.com/1565140/

Thanks,
-Geoff

>>>I do see that the drives come up as UDMA 133, not sure how to interpret
>> that.
>>
>> That seems odd to me. The sata controllers should be set to AHCI,
>> especially
>> for the SSD. The RAID option automatically uses AHCI, but onboard RAID
>> tends
>> not to  work well with Linux. It doesn't sound like you're using RAID in
>> any
>> case. I see in your mainboard's manual that AHCI is disabled by default.
>>
>> Also in the manual, I see there is only one SATA 3 port. This runs at
>> 6Gb/s
>> and is the port you should have your SSD connected to.
>>
>
> Yes the SSD is connected to SATA3, is configured as AHCI in bios and no
> RAID is enabled.
>
>
>>>I then tried to run the benchmark using the Disk Utility but it gave an
>> error for every drive: "Error seeking to offset <number>"
>>
>> Something is wrong with this as well. The benchmark should just run. I
>> have
>> had problems with video cards and Ubuntu version 12.10, so try booting
>> the
>> Live version of 12.04 and see if you can run the benchmarks. The Disk
>> Utility in 12.10 is different than the one used in previous versions.
>>
>
> I booted the 12.04 Ubuntu live disc and recorded some data.
>
> Disk Utility:
>   All drives are detected as connected via SATA
>     SSD Benchmark Results:
>       Min Read Rate: 556.4 Mb/s
>       Max Read Rate: 565.6 Mb/s
>       Average Read Rate: 564.0 Mb/s
>       Average Access Time: 0.1 ms
>
> I also collected a few hdparm results:
>
> ubuntu at ubuntu:~$ sudo hdparm -tT /dev/sda
>
> /dev/sda:
>  Timing cached reads:   17816 MB in  2.00 seconds = 8920.25 MB/sec
>  Timing buffered disk reads: 1538 MB in  3.00 seconds = 512.09 MB/sec
> ubuntu at ubuntu:~$ sudo hdparm -tT /dev/sda
>
> /dev/sda:
>  Timing cached reads:   17956 MB in  2.00 seconds = 8988.25 MB/sec
>  Timing buffered disk reads: 1538 MB in  3.00 seconds = 512.11 MB/sec
> ubuntu at ubuntu:~$ sudo hdparm -tT /dev/sda
>
> /dev/sda:
>  Timing cached reads:   18128 MB in  2.00 seconds = 9085.92 MB/sec
>  Timing buffered disk reads: 1538 MB in  3.00 seconds = 512.13 MB/sec
>
> I also collected all the same pastebin data for the 12.04 live disc and
> posted it. I am working on comparing the two:
>
> http://paste.ubuntu.com/1565140/
>
>>
>>> I did the memtest86 to determine RAM speed. It is listing at 17118 MB/s
>> and 32 GB size.
>>
>> That seems fine. And it sees the entire 32GB of ram. My i5-2400 uses
>> DDR3-1600 ram and runs at 18975 MB/s. I think the only difference is the
>> type of ram we use. No errors running memtest86+, then? Did you let it
>> complete a pass?
>>
>
> I did not let it complete a pass. I should at some point (new hardware and
> all), but since I am not suspecting the ram I did not do that
>
>>
>>> Pastebin: http://pastebin.ubuntu.com/1561660/
>>
>> I don't see anything that stands out here, although it's a lot of
>> information and maybe someone else will see something I've missed...
>>
>> One thing I do notice is your ethernet controller: "RTL8111/8168B" These
>> controllers have been a source of problems in the past because of driver
>> issues, however, I thought those issues were largely resolved. (Oh, I
>> see
>> you mentioned that the speed of the downloads were not a problem, so
>> ignore
>> this)
>>
>>
>>> Also I see a GUID partition table with an error.
>>>
>>> WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util
>>> fdisk
>> doesn't support GPT. Use GNU Parted.
>>
>> Is this the error you see? This is normal and just means the fdisk
>> program
>> cannot handle drives with GPT partition types because the program is too
>> old.
>>
>>
>
> Yes that is the error I saw. Thanks for the explanation, I was not certain
> what to make of it.
>
>>
>>
>>
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>
>