LSI 9240-4i 4K alignment

[Steven Hartland]

----- Original Message ----- 
From: "Don Lewis" <truckman at FreeBSD.org>
To: <killing at multiplay.co.uk>
Cc: <gkontos.mail at gmail.com>; <freebsd-stable at FreeBSD.org>; <freebsd-hardware at FreeBSD.org>
Sent: Sunday, August 19, 2012 6:37 PM
Subject: Re: LSI 9240-4i 4K alignment


> On 16 Aug, Steven Hartland wrote:
>> ----- Original Message ----- 
>> From: "George Kontostanos" <gkontos.mail at gmail.com>
>>  
>>> You are right, the chip specs say: LSISAS2108 RAID-on-Chip
>>> 
>>> The drives are identified as mfisyspd0, mfisyspd1, etc.
>> 
>> The following might be interesting to you:-
>> http://forums.servethehome.com/showthread.php?599-LSI-RAID-Controller-and-HBA-Complete-Listing-Plus-OEM-Models
>> 
>> Which states:-
>> LSI MegaRAID SAS 9240-4i 1x4 port internal SAS vertical,
>> no cache, no BBU, RAID 0, 1, 10 and 5, can be crossflashed
>> to LSI9211 IT/IR
>> 
>> This is insteresting as this is the card we're using but
>> in the 8 port version under mps :)
> 
> I wish I would have known this earlier.  I just put together a ZFS
> server using LSI MegaRAID SAS 9240-8i cards.  The cabling probably would
> have been cleaner with the 9211-8i, but I went with the 9240 because the
> vendor that I purchased the cards from listed that 9240 as being
> PCI-Express 2.0, but didn't say that about the 9211.  I also got the
> impression that the 9240 recognized JBOD drives with the off-the-shelf
> firmware, whereas the 9211 did not.
> 
> Even LSI's own site is a bit confusing.  They list the 9211 in the HBA
> section, but its specs don't mention JBOD, whereas the 9240 is listed in
> the RAID section and its specs do list JBOD.  If the only physical
> difference between the cards is the connector position, it seems odd
> that they don't offer products with all the combinations of firmware and
> connector position.
> 
> I haven't configured the ZFS pool yet, but I didn't have any trouble
> installing FreeBSD 9.1-BETA on the GPT partitioned boot drive, which
> shows up as an mfi device.  I'm planning on getting the ZFS pool up and
> running in the next few days.

HBA's are the way to go if your using ZFS to manage the disks, you only
need RAID if your using a FS which doesn't manage the disk side well
such as UFS.

Its often quite common for RAID controllers to actually be slower
vs RAID controllers as the RAID stack can get in the way.

JBOD is generally what HBA's do by default which may be the reason
why LSI's site doesn't mention it.

    Regards
    Steve

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