freebsd-performance Digest, Vol 4, Issue 7

Eric Anderson anderson at
Wed Jun 18 13:44:28 PDT 2003

Jin Guojun [DSD] wrote:
> Eric Anderson wrote:
>>>Very minimum.
>>>It was slow on SCSI bus , but I do not have time to diagnose,
>>>which can be very time consuming.
>>My tests have shown that a GOOD hardware RAID5 controller can really
>>help you out when it's being slammed (specially over NFS) - I use Dell
>>PERC/2 and PERC/3 controllers (rebranded AMI RAID boards).  They run
>>like champs, and I get 40MB/s sustained xfers..
> What did you mean sustained xfers ? -- in and out, or just read out.

sustained writes (not burst transfers) and sustained reads.. With 
hardware RAID's that have cache memory on them (as the PERC's do - mine 
has 128mb), you can get huge burst speeds (all in memory, so it makes 
sense).  If you have a machine that is writing small files constantly, 
the cache can significantly help.  However, putting a lot of extra 
memory in the server running a software RAID can do this with similar 
results.  I always suggest piling on the RAM for servers..


Eric Anderson	   Systems Administrator      Centaur Technology
Attitudes are contagious, is yours worth catching?

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