[LUNI] Need help determining what's causing a server to be slow

[Ramin K]

Branko Kotur wrote:
> I've recently put together 2 new servers to replace older existing ones.  
> However, whenever these new servers do any kind of disk intensive access, 
> they seem to fall flat on their faces to the point where they're at times 
> unresponsive (for example, untarring a 1GB tar file).  The only thing I can 
> think of is that something isn't configured right as they should basically 
> blow away the older servers that I'm using.  Even doing a simple operation 
> like ls in a director that only had 10 files takes forever.
> 
> Whenever I've noticed the unresponsiveness, the load tends to be around 4 - 8 
> with the IO Wait (as reported by top) is anywhere from 80% - 100% for 1 or 
> both CPU's.  I'm wondering if the bottleneck is the RAID card or the driver 
> for the card.  I'm also wondering if the PCI-X slot (that the RAID card is 
> plugged into) may be the bottleneck.
> 
> Some info on these servers:
> 
> Dual core Opteron 180, 4GB RAM, 3ware 9550SX RAID card, CentOS 4.4 64bit, WD 2 
> Caviar RE SATA 3.0G/s drive in RAID 1, Supermicro H8SSL-i motherboard.
> 
> CentOS 4.4 comes with the 3ware drivers as part of the install CD so I didn't 
> think I needed to install them separately.  However, the actual file is much 
> smaller then the one provided by 3ware (53K as opposed to the 313K version 
> offered by 3ware).  Is the included one just a basic driver?  3ware seems to 
> offer open source drivers, so I don't see why the included one would be any 
> different then the official one.  

libata has been a fairly quick moving target. It's possible that your 
current kernel has an older version which has issues. I've seen similar 
behavior on SI SATA cards that switched chipsets on us between revisions.

Ramin