Dell Perc 6 disk geometry problem with RAID5 (both 6.3 final and 7.0 RC1)

David Wood david at
Sun Jan 20 09:28:28 PST 2008

[ambrisko@ and scottl@ added to CCs]

Hi there,

In message <9c1614e00801200608k49195944mf241b7b0aa6a48 at>, 
Aldas Nabazas <freebsd.stable1 at> writes
>We bought a new Dell PowerEdge 2950III with Perc 6/i and have the disk
>geometry problem using 6.3 final or 7.0 RC1. Seems that we are not alone at
>least one guy has similar problem reported earlier:
>I was reading the mailing list and found that some of the people are happily
>using this hardware with the latest FreeBSD:
>I just wonder what the status of mfi driver? Maybe it's not fully tested or
>there will be some important fixes before 7.0 final? We are going to try
>different RAID combinations but it definitely not working using 6x146GB as

This is extremely disappointing to read, as I was relatively close to 
buying a Poweredge 2950 III with PERC 6/i. However, it's no good to me 
if mfi(4) has issues with large virtual disks; the tentative disk 
configuration is 2x146GB as RAID 1 and 4x750GB (or 1TB) as RAID 5.

Looking at CVSweb:

the updates for the 1078 chip which powers the PERC 6 series were 
contributed by LSI, so you would have hoped things were right. There is 
a disclaimer on the code, but you would also hope that someone in the 
know is testing it, especially as my impression has always been that the 
FreeBSD community is favourably disposed towards LSI storage controllers 
and that LSI and their vendors try to help the FreeBSD developers.

>Maybe someone could share the RAID combinations they successfully are
>running on?

I haven't been keeping a very close eye on the problem as I don't 
currently have any hardware - but is the issue simply one of virtual 
disk size - there's a cut-off size after which things don't work 

You could try pulling disks from your server (or removing them from the 
virtual disk) one by one until things start to work. To save a lot of 
pain you could create a virtual disk containing one disk as RAID 0 (a 
single disk) and install the OS on it, leaving the other five disks to 
play with.

I do hope that someone is in a position to investigate this quickly - 
even if it's too late to get the fix in 7.0-RELEASE now. There's nothing 
that I can see as relevant that's waiting for MFC, anyway.

Of course, it's worth checking whether you've got the latest firmware on 
the PERC 6/i - the latest version from Dell appears to be 6.0.1-0080.

If this doesn't get fixed soon, I'm either going to have to go to 
another hardware vendor that uses a different RAID controller (HP is a 
possibility - though we're an all Dell shop) or - sniff - leave FreeBSD 
in favour of a Linux distribution. I realise that FreeBSD is a volunteer 
project, and that users can't have any specific expectations - this is 
not a threat, as I like FreeBSD and want to remain in the community, but 
I would need a new server to work properly!

Looking at CVSweb, it seems that ambrisko@ and scottl@ are the two 
people most closely associated with the mfi code - I've added them into 
the CCs. My apologies if that was unwelcome.

Best wishes,

David Wood
david at

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