Disk flashes every second under OSR6

[stankow]

I installed OSR6 on IBM xServer226 8848-E4Y with ServerRAID 6i. It works fine, disk subsystem is fast, mirroring works as expected.

But every 1 or 2 seconds both mirror disks flash.
And there is a noice from heads positioning.

Same is with "planar" SCSI controller, without ServeRAID.

No problem with same computer, but under OS 5.0.7

Does anybody knows what a backend process produce it ? It is not only annoying noice, but afraid it could damage the disk in short time !

Regards !

Stankow,

http://www.noac.biz

 

[motoslide]

There is a kernel parameter which tells the system how often to flush disk buffers back to disk. In versions 5.0.7, the default was quite long (every 30 seconds, I think). This gave us a system which was quick for a few seconds, then had a noticeable delay as the buffers were flushed back to disk. We achieved an overall faster machine by changing that parameter to flush every second, which would create the symptom you describe.
I haven't had to play with that same parameter in SCO6. Check the FDFLUSHR and NAUTOUP parameters. The default for FDFLUSHR is 1 second. You could experiment with extending that time, but I've found that the performance is best to leave it alone.

"Proof that there is intelligent life in Oregon. Well, Life anyway.

 

[stankow]

thanks, motoslide.

I check it, rebuild the kernel, but it still stay. NAUTOUP is 60. FDFLUSHR is 1, but it is the time in seconds to check, if it is changed, not to write ultimatively. I set it to 10, no changes.

Could be some process internal to RAID controller, say some "sync" between mirrored disks. But process starts only if the OSR6 is loades, maybe the driver put the controller in such mode.

Stankow,

http://www.noac.biz

 

[motoslide]

I honestly wouldn't give it much concern. It certainly could be built into the RAID driver. The first time I modified a 5.0.7 system to update every 1 second, I thought it was odd to see (and hear) the rhythmic updating of the disks, but once I ran some benchmarks to determine the write performance, I made it one of my standard "post-install" tasks. When I revisit a particular site, if the disks AREN'T flashing every second, I know I forgot to make that adjustment.

Maybe your activity is based on some other background process? You can try going into single-user mode to see if the behavior changes. There are fewer processes running. Were you able to confirm that FDFLUSHR is set to "10"? You can run sysdef to display the current settings.

"Proof that there is intelligent life in Oregon. Well, Life anyway.

 

[stankow]

>I honestly wouldn't give it much concern.

I'm worried if it can worn out the disks arms. And also noice - the server should run in dispatch centre, no need to increase the noice from fans additionaly.

> It certainly could be built into the RAID driver.
It's strange, not very rhythmic.

>some benchmarks to determine the write performance,

I wonder why the performane improve ?? Can not catch the reason.

>Maybe your activity is based on some other background process?
Could be. But how to determine it ?
Even my favorite u386mon do not work under OSR6. Actually OSR6 is very different from predecessor as never since Xenix -> ODT transition

>You can try going into single-user mode to see if the
No changes, same behavior.

>Were you able to confirm that FDFLUSHR is set to "10"?

Yes, the new graphical configurator (tuner) is good and easy

>You can run sysdef to display the current settings.

I use it, thanks you teach me to one new (for me) command - sysdef !!

Stankow,

http://www.noac.biz