Re: ARC-1120 and MD very sloooow

Right.  It's unusual to see this many mount options.  FYI, the XFS
default is relatime, which is nearly identical to noatime.  Specifying
noatime won't gain you anything.  Do you really need nosuid, nodev, noexec?

Well better say what I don't want on the filesystem no?

 >Do you also see the low write speed and slow ls on md0, any/all of your

md/RAID10 arrays?

Yes, all drive operations are slow, unfortunately, I have no drives in
the machine
that are not managed by the controller to push tests further.

The usual: "iostat -x -d -m 5" output while the test is running.
Also, you are using buffered IO, so changing it to use direct IO
will tell us exactly what the disks are doing when Io is issued.
blktrace is your friend here....

I've ran the following:


    # dd if=/dev/zero of=/srv/store/video/test.zero bs=512K count=6000
oflag=direct
    6000+0 records in
    6000+0 records out
    3145728000 bytes (3.1 GB) copied, 179.945 s, 17.5 MB/s

    # dd if=/srv/store/video/test.zero of=/dev/null iflag=direct
    6144000+0 records in
    6144000+0 records out
    3145728000 bytes (3.1 GB) copied, 984.317 s, 3.2 MB/s


Traces are huge for the read test so I put them on Google Drive + SHA1 sums:
https://drive.google.com/folderview?id=0BxJZG8aWsaMaVWkyQk1ELU5yX2c

Drives `sdc` to `sdf` are part of the RAID10 array. Only drives `sdc` and `sde`
are used when reading.

That makes me wonder if the controller and drive write caches have been disabled.
That could explain this.

Caching is enabled for the controller but not much information.


    > sys info
    The System Information
    ===========================================
    Main Processor     : 500MHz
    CPU ICache Size    : 32KB
    CPU DCache Size    : 32KB
    CPU SCache Size    : 0KB
    System Memory      : 128MB/333MHz/ECC
    Firmware Version   : V1.49 2010-12-02
    BOOT ROM Version   : V1.49 2010-12-02
    Serial Number      : Y611CAABAR200126
    Controller Name    : ARC-1120
    ===========================================


By the way is enabling the controller cache a good idea? I would disable
it and let the kernel manage.

--
Jimmy