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Re: Severe netbsd-6 NFS server-side performance issues
At 12:45 Uhr -0700 30.5.2012, Brian Buhrow wrote:
>Hmm. A panic a week? I wouldn't call that stable at all.
That's relative... ;)
>However, one issue at a time.
> Does the raid controller have some sort of battery backed up cache?
>Which driver supports these raid controllers? mfi(4)?
amr0 at pci4 dev 0 function 0: AMI RAID <MegaRAID SCSI 320-4X>
amr0: interrupting at ioapic2 pin 4
amr0: firmware 421D, BIOS H434, 256MB RAM
ld0 at amr0 unit 0: RAID 5, optimal
ld0: 1675 GB, 218759 cyl, 255 head, 63 sec, 512 bytes/sect x 3514368000 sectors
-- I had fun upgrading the firmware (the original version would install the
RAID, but not boot), since the controller turned out to be a Fujitsu OEM,
although it said LSI all over the board, and LSI refused to support it. In
the end, I pried out a totally undocumented firmware from an iso image off
an obscure Fujitsu ftp server. It worked, and even fixed the immediate
> I'm not sure of the problem, but it sounds like some sort of write
>back cacheing switch got flipped in the raid controller, and now writes,
>with interleaving reads, are really slow. I'm assuming you've looked at
>the BIOS of the raid controller to see if there are any settings which
>might have to do with caching?
Yes, and they are as I wanted them, battery present, cache set to
write-back. I ran bonnie++ on the array last week to check whether the
dismal performance is disk related. From the results I got I'd say it is
> Is it possible to revert to the NetBSD-5.x system and see if your
>performance goes back to where it was after the raid upgrade but before
>the OS upgrade?
Tricky. The installation is netbsd-6, and the disk array is well-filled, so
I'd have to attach a sata disk for the netbsd-5 system, plus rebuild the
packages installed. Might be worth a try, though, although as I said, the
netbsd-5 stability was not satisfactory.
> If you export a non-raid disk, what kind of nfs performance do you get
>on the system when writing to that disk? (That will help you figure out if
>it's a raid problem or an OS problem.)
Hm - I could try that quickly tomorrow. Might well give some information.
OTOH, the bonnie++ run appears to have cleared the disk subsystem.
> I realize that I'm more questions than answers, but I think the
>question you're trying to answer is, what changed? The answer is, I think,
>something about the raid system.
Nothing really changed, that's what baffles me. The machine rebooted after
a panic at some point, and came up with bad performance. I had updated the
kernel in that context, but as I mentioned, the old kernel gave the same
At this point, I am very much banging my head against a wall, so questions,
by forcing me to re-think the situation from the ground up, are quite
"It's never straight up and down" (DEVO)
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