Slow disk I/O - was Re: Seeking Help

[geoff at thebakershome.net]

>>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.

>
>
>
> --
> ubuntu-users mailing list
> ubuntu-users at lists.ubuntu.com
> Modify settings or unsubscribe at:
> https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
>