Re: Poor performance (especially writes)

[Christopher Smith <csmith@nighthawkrad.net>]

Christopher Smith wrote:
> (Apologies if this is a repost, but I haven't seen it appear four hours 
> later and there's no indication the list is moderated...)
> 
> Hello, all,
> 
> I am having some trouble extracting good (or even average) performance
> out of my NFS server, particular for writes, and was hoping to get some
> suggestions as to how to improve it.

After a day of experimentation, I believe I've nailed this down as being 
related to Dell's SAS 5/i disk controller.  A regular SATA drive using 
the onboard SATA controller in this machine shows about 10x the 
performance untarring the smaller image files over NFS.

So, it would appear to be some weird interaction between NFS and Dell's 
SAS 5/i disk controller (rebadged LSI device):

02:08.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068 PCI-X 
Fusion-MPT SAS (rev 01)
         Subsystem: Dell: Unknown device 1f09
         Flags: bus master, 66Mhz, medium devsel, latency 72, IRQ 169
         I/O ports at ec00 [disabled] [size=256]
         Memory at fe9fc000 (64-bit, non-prefetchable) [size=16K]
         Memory at fe9e0000 (64-bit, non-prefetchable) [size=64K]
         Expansion ROM at fea00000 [disabled] [size=1M]
         Capabilities: [50] Power Management version 2
         Capabilities: [98] Message Signalled Interrupts: 64bit+ 
Queue=0/0 Enable-
         Capabilities: [68] PCI-X non-bridge device.
         Capabilities: [b0] MSI-X: Enable- Mask- TabSize=1



I have duplicated this problem with RHEL installed and reported it to 
Red Hat.  Anyone else interested ?


-- 
Christopher Smith

Systems Administrator
Nighthawk Radiology Services
Level 11, Suite 1101
Grosvenor Place
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Australia

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