Mylex (Buslogic) BT-950 vs. BT-958

Mylex (Buslogic) BT-950 vs. BT-958

Post by Janne Himank » Tue, 12 Jan 1999 04:00:00



We currently have two BT-950 (Flashpoint) UW SCSI adapters in a dual
PII 450 MHz machine. One adapter has three Seagate Cheetahs, the other
two. One disk is root, the remaining 4 comprise one raid0 partition. I have
been benchmarking, and while speed is excellent, I am worried about
the cpu consumption. Bonnie says

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         2000  8629 98.0 58084 80.2 22013 70.8  9037 96.7 52675 89.3 405.4  7.2

Even block writes use 80% of cpu. I also used time(1) on this Bonnie
process, and it reported that 40% of the cpu comsumption was system,
60% user.

Iozone reported similar speeds but system cpu consumption was 95%,
user cpu 5%. Is there any way to determine, what that system cpu usage
is? Is it mainly Linux raid implementation's overhead or is it the
Mylex drivers?

I tried also with raid5, and cpu consumption was about the same, plus
the md_thread process taking around 13% of cpu.

Finally, it would be nice to know if upgrading to BT-958 is worth the
price differential.

Janne Himanka
--

fixing everybody's troubles, everybody's but mine, + Learning & Res. Services
someone must have told them that I was doing fine. + Oulu University, Finland

 
 
 

1. Mylex (former BusLogic) BT-958 BT-958D adapter problem.

Hi to All.

   Would you all be so kind to help me in the troubleous situation.

   The question is the following: does any FreeBSD version supports bt-958
Mylex adaptor properly?

   I have tested insalling FreeBSD 2.2.6-RELEASE on a server with SUBJ,
but it was automaticaly recognized as BusLogic BT-946 adapter and had
worked only at 20 Mbytes/sec rate. The same problems I had faced under
3.0-110398-SNAP.
   While looking through the LINT kernel configuration file I had not
found any suitable deceision on how to solve the problem.

   Are there any additional options in kernel config to make SUBJ to work
at 40 Mb/sec?
   Is there any well known experience in solving problems of shuch a sort.
   If this adapter family is supported properly in any FreeBSD
Unix version or anywhere else (exept NT), permitting me to use it at
its maxinum rate?
   Are there any adapers compatible with subj, that support 40 Mb/sec
transfer rate?
   Are there any third party FreeBSD drivers for the subj.

   If anyone has experience in installing/maintaining the SUBJ under
FreeBSD, would he be so kind to share it with me.

--                                      Thanks in Advance,
                                        Best regards. Iliah V. Serov
                                        LEK Telecom ISP, St Petersburg
                                        Russia.

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