Jens Neu writes:
> > I think ext3 is a bit slow on so big LUNS, try xfs or similar?
>
> there is no official support for xfs in RHEL5, so that is not an option.
> Besides, I'm talking about a drop of >150mb/s to ~10mb/s read performance
> when cracking the 2.2T size. This is clearly not in the ext3 (or FS for
> that matter) magnitude of performance issues. Also, numbers stay the same
> when dd'ing on the raw device (LUN).
This may not be relevant for you at all, but I have seen a comparable drop in
read performance on a new Dell machine (hdparm -t, 25MB/s vs. 130MB/s),
completely unrelated to the disk type. In this case, I had to add
"pci=nommconf" to the kernel line in grub.conf. This was specific to the RH
kernel, live CDs with 2.6.32 or .34 kernels were fine. I also noticed that
booting up older IBM Intellistations under CentOS gave a warning about a BIOS
bug ("MCFG area at e0000000 is not E820-reserved"; whatever that means :) and
not using mmconfig.
Also make sure that all BIOS options are set correctly, if applicable.
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