IR mode actually passing through drives?

AugustaLemke

New Member
Sep 6, 2021
15
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I recently purchased a H12SSL-CT motherboard with a Broadcom 3008 SAS3 controller. I booted into Linux and was SHOCKED to see the drives in /dev/disk/by-id. I had thought it was somehow factory default in IT mode but it was still in IR when I went to check. In my previous experience IR mode doesn't pass through the drives. Times have changed I guess (I need to get with the times apparently).

My original goal was to use flash it to IT mode and use software RAID. Does it still make sense to flash it to IT mode? I'm not even sure what benefit flashing IT mode gives me now since IR passes through the drives.
 
Last edited:

TRACKER

Member
Jan 14, 2019
99
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Hello,
i never had to flash controller in IR mode to IT.
I have SAS2008 and SAS2308 and both in IR mode pass through drives and each drive is visible in OS as separate drive.
Even smart capabilities are available :)
I was always wondering why people flash to IT mode their cards, perhaps there are sometimes cases when this is necessary.
 

edge

Active Member
Apr 22, 2013
177
55
28
I recently purchased a H12SSL-CT motherboard with a Broadcom 3008 SAS3 controller. I booted into Linux and was SHOCKED to see the drives in /dev/disk/by-id. I had thought it was somehow factory default in IT mode but it was still in IR when I went to check. In my previous experience IR mode doesn't pass through the drives. Times have changed I guess (I need to get with the times apparently).

My original goal was to use flash it to IT mode and use software RAID. Does it still make sense to flash it to IT mode? I'm not even sure what benefit flashing IT mode gives me now since IR passes through the drives.
I would expect it to show individual drives until you defined an array. The bigger question is if does trim and other functions to the drives or is it is filtering those and just defaulting to a one drive raid 0.
 

Zedicus

New Member
Jul 12, 2018
21
7
3
LSI cards (99% of them) pass through drives to the host even in IR mode (as long as no array is configured at all). there is a SMALL performance hit using IR mode with passthrough, 1 - 3% on average. and SMART MIGHT not work, depending on several factors.

for a novice builder, there is no real gain by flashing to IT. only go through the trouble if your distro requires you to upgrade firmware anyway, or you have some compelling reason to do so.