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12 TB HDDs and LSI 9211 (SAS2008)?

digity

FreeNAS Experienced
Joined
Apr 24, 2016
Messages
104
Anyone one know if the LSI 9211 (SAS2008) HBA card works with 12 TB hard drives? If not 12 TB, how about 10 TB?
 

kdragon75

FreeNAS Expert
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Aug 7, 2016
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2,449
I don't see why it wouldn't. everything I have seen simply states "supports >2TB disks".
 

digity

FreeNAS Experienced
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Apr 24, 2016
Messages
104
I don't see why it wouldn't. everything I have seen simply states "supports >2TB disks".
Oh, okay. So 2 TB is the barrier when it comes to this type of stuff? Just curious, is the limiting factor the card's hardware or firmware or the computer's OS or device drivers?
 

Arwen

FreeNAS Expert
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May 17, 2014
Messages
1,144
@digity, the issue with 2TB drives is that some early SAS 1 equipment had trouble with >2TB drives. They did not exist when the standard was written.

Today, no one should buy SAS 1 equipment, (disks, SAS cards / HBAs, or expanders). It's just too old. (In general, SAS 1 was fine for it's day, but like all version 1 standards, it has it's problems.)

The LSI 9211 (SAS2008) HBA card is SAS 2 if I remember correctly. SAS 3 cards are not quite as cost effective yet. And SAS IV / 4 is just coming out, so probably no software support by FreeBSD / NAS.
 

Ericloewe

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Feb 15, 2014
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16,110
is the limiting factor the card's hardware
Old hardware, notably LSI SAS1 controllers, only supports LBAs up to 32 bits. SAS clearly decided to cheap out on their internal buffers or something and SAS1 controllers only show 2^32 LBAs. That means 2 TB with 512 byte sectors.
 

Arwen

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May 17, 2014
Messages
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Old hardware, notably LSI SAS1 controllers, only supports LBAs up to 32 bits. SAS clearly decided to cheap out on their internal buffers or something and SAS1 controllers only show 2^32 LBAs. That means 2 TB with 512 byte sectors.
Actually it's not so much the limit of SAS version 1, as the limit of the under-lying SCSI protocol. I think they now use 2^48 bit addressing for blocks. Eventually they will have to go to 56 or 64 bit addressing. If I remember correctly, I was around when they transitioned from 24 bit addressing to 32 bit. (May even have been around for the 16 bit to 24 bit change...)
 

kdragon75

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Aug 7, 2016
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FAT12...
 

Ericloewe

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Actually it's not so much the limit of SAS version 1, as the limit of the under-lying SCSI protocol. I think they now use 2^48 bit addressing for blocks. Eventually they will have to go to 56 or 64 bit addressing. If I remember correctly, I was around when they transitioned from 24 bit addressing to 32 bit. (May even have been around for the 16 bit to 24 bit change...)
It's not an SAS1 limitation, it's an LSI SAS1 hardware limitation, as far as I know. I couldn't find anything about what the SCSI version that SAS implements supports, however I did find LSI's short little document on the matter:
https://www.supermicro.com/support/faqs/data_lib/S11196_v1.0_Support_for_Drives_Greater_than_2_TB_for_SAS1_IT_IR_Products.pdf

Curiously enough, it implies that SAS disks larger than 2TB are indeed fully supported with P13 or later firmware, but then says that the changes required to address 48-bit LBAs are not planned for SAS1 devices... Gotta love how marketing twists things.
 

Ericloewe

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BTW: 48-bit LBAs support up to 144 PB with 512-byte sectors or 1.1 EB with 4k sectors. Since 48-bit logic is simplest to implement as 64-bit logic, since that's the next step up that every microarchitecture has, current hardware probably could handle 64-bit LBAs with simple firmware changes, for 9.4 ZB with 512-byte sectors and 75.6 ZB with 4k sectors. I don't think we'll be running into problems that soon, particularly as sector sizes are bound to increase.
 
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