[CentOS] RAID card selection - JBOD mode / Linux RAID

Wed Jul 18 19:50:03 UTC 2012
Alan McKay <alan.mckay at gmail.com>

I don't think this is off topic since I want to use JBOD mode so that
Linux can do the RAID.  I'm going to hopefully run this in CentOS 5
and Ubuntu 12.04 on a Sunfire x2250

Hard to get answers I can trust out of vendors :-)

I have a Sun RAID card which I am pretty sure is LSI OEM.  It is a
3G/s SAS1 with 2 external connectors like the one on the right here :


And I have 2 x Sun J4400 JBOD cabinets each with 24 disks.

If I buy a new card that is 6G/s SAS2 with the same connector, can I
connect my cabinets to it and have them work?  Even if they only work
at 3G/s I don't care.

I've also hit an issue with the number of logical devices allowed, and
am wondering whether this might be a HW, FW or SW limitation if anyone

I want to run everything in JBOD mode and let Linux do the RAID.   So
for the first cabinet I ran this command 24 times to create a logical
drive for each physical one

/usr/StorMan/arcconf create 1 logicaldrive max volume 0,X noprompt

Where X goes from 0 to 23

Went great, created /dev/sd[c-z] and I was able to use those with
mdadm to create 4 x RAID6 arrays and then a big RAID0 out of the 4 x
RAID6.  Works great!

Then I try to connect the 2nd cabinet and when I run the above arcconf
command it tells me there are already 24 logical devices, and this is
the max.

Anyone know whether that is HW, FW or SW?

Would a new card fix this problem?   Anyone know for sure of a card
with above connectors that has a JBOD mode that will support 48 drives
and expose them all to Linux?

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