Please help - adaptec 2820sa not ... RESOLVED

Eric Anderson anderson at
Wed Jun 21 03:20:32 UTC 2006

Scott Long wrote:
> Eric Anderson wrote:
>> Ensel Sharon wrote:
>>> On Mon, 19 Jun 2006, Jahilliya wrote:
>>>>> Ok, aac is in the dmesg.
>>>>> I can see both 2820sa cards in the dmesg, and I see no errors, etc. -
>>>>> there are just no drives listed in dmesg.
>>>>> My setup is 8 500 Gb drives in a single raid-6 array, size ~2.8TB.  
>>>>> Any
>>>>> problems with that ?  Perhaps sysinstall cannot deal with a >2TB drive
>>>>> ?  There are no other drives in the system besides the single 2.8TB 
>>>>> raid 6
>>>>> array ...
>>>> Have you got any other drives you can attach to the raid?
>>>> If so, disconnect the 8 drives connected, connect up a couple that are
>>>> not part of the raid and configure them as a simple raid 1 and see if
>>>> the installers sees that raid. Or try any combination in drives to
>>>> bring the raid size down below 2TB (I'm sure this limitation has been
>>>> fixed.)
>>> Ok, the answer is that it has not been fixed.
>>> 6.1 sysinstall does in fact see both 2820sa controllers, and when I 
>>> put in
>>> a single 160GB sata drive, it does see that single drive and I can 
>>> install
>>> onto it, etc.
>>> Sysinstall does _not_ see my 2.7TB raid6 array.  I suspect that if it 
>>> were
>>> smaller than 2TB, it would see it correctly.
>>> I have a number of options with which to deal with this, all of which
>>> involve either wasting money or wasting disk space.  Fantastic.
>> Right - FreeBSD doesn't recognize >2TB LUNs.
> Wrong on several counts.  First, the AAC driver does not present arrays 
> to the system as SCSI LUNs.  The traditional 2TB limit with 12 byte CDB
> issue simply doesn't exist with this driver.  Second, the FreeBSD SCSI
> layer knows how to issue 16 byte CDBs to access >2TB, assuming that the
> target understands the 16-byte protocol.  So no, there is no 2TB limit
> inherent to FreeBSD.  The only limit is with individual drivers and with
> hardware.
> Scott

Scott, thanks for correcting me on this.  I was under the (false) 
impression that this was a FreeBSD SCSI issue, not a driver issue.  I 
had tried this with QLogic fiber (fabric) storage in the past, and had 
issues, so I incorrectly thought that the information I had was true.

Is it difficult to make drivers (such as the qlogic isp driver) handle 
 >2TB devices?


Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.

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