Re: Playing with SATA NCQ

[Michael Thonke]

Jens Axboe wrote,

>
>There's really nothing to be tuned. If NCQ is enabled for your drive, it
>will be printed in dmesg after the lba48 flag, such as:
>
>ata1: dev 0 ATA, max UDMA/133, 488281250 sectors lba48 ncq
>
>If you don't see NCQ there, your drive/controller doesn't support it.
>Likewise you will have a queueing depth of > 1 if NCQ is enabled, check
>/sys/block/sdX/device/queue_depth to see what the configured queueing
>depth is for that device.
>
>  
>
Hi Jens,

thanks for the short info now my next question how many queue depths
are healty and wanted?

For my Intel Corporation 82801GR/GH (ICH7 Family) Serial ATA Storage
Controllers cc=AHCI (rev 01)
and Samsung Hd160JJ SATAII drive the default queue is 30

    ioGL64NX_MACH~# cat /sys/block/sda/device/{model,queue_depth}
    SAMSUNG HD160JJ
    30

    hdparm -Tt /dev/sda

    /dev/sda:
    Timing cached reads: 4724 MB in 2.00 seconds = 2360.00 MB/sec
    Timing buffered disk reads: 164 MB in 3.02 seconds = 54.28 MB/sec

On random access the drives is a bit noisy but the subjective feeling is
great
everything goes a bit faster.

And whats about the option /sys/block/sdx/device/queue_type = simple
what can be done here?

Thanks in advance
Best regards
Michael



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