Messages in this thread | | | Date | Fri, 6 Jul 2007 15:25:16 +0100 | From | "Daniel J Blueman" <> | Subject | Re: Understanding I/O behaviour |
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On 5 Jul, 16:50, Martin Knoblauch <spamtrap@knobisoft.de> wrote: > Hi, > > for a customer we are operating a rackful of HP/DL380/G4 boxes that > have given us some problems with system responsiveness under [I/O > triggered] system load. [snip]
IIRC, the locking in the CCISS driver was pretty heavy until later in the 2.6 series (2.6.16?) kernels; I don't think they were backported to the 1000 or so patches that comprise RH EL 4 kernels.
With write performance being really poor on the Smartarray controllers without the battery-backed write cache, and with less-good locking, performance can really suck.
On a total quiescent hp DL380 G2 (dual PIII, 1.13GHz Tualatin 512KB L2$) running RH EL 5 (2.6.18) with a 32MB SmartArray 5i controller with 6x36GB 10K RPM SCSI disks and all latest firmware:
# dd if=/dev/cciss/c0d0p2 of=/dev/zero bs=1024k count=1000 509+1 records in 509+1 records out 534643200 bytes (535 MB) copied, 11.6336 seconds, 46.0 MB/s
# dd if=/dev/zero of=/dev/cciss/c0d0p2 bs=1024k count=100 100+0 records in 100+0 records out 104857600 bytes (105 MB) copied, 22.3091 seconds, 4.7 MB/s
Oh dear! There are internal performance problems with this controller. The SmartArray 5i in the newer DL380 G3 (dual P4 2.8GHz, 512KB L2$) is perhaps twice the read performance (PCI-X helps some) but still sucks.
I'd get the BBWC in or install another controller.
Daniel -- Daniel J Blueman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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