Disk enumeration - Supermicro X8SI6-F

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So, the other day I was gifted an old server, based on the Supermicro X8SI6-F.

It sits in a Fractal Design Define R5, that easy supports 8+ drives.

As always, the first thing that came to mind, was that this could be used with XPEnology ;-)


It has no problem booting Jun's 1.3b, and installing DSM 6.3.x (DS3615xs),

but it insists on using the 6*Sata2(3Gb/s) as drive 1-6, before the 8*6Gb/s ports on the integrated SAS controller (IT-mode).

This give me a count of 6+8=14 drives, and if I want to use them all, I will have to modify the max disk in synoinfo.conf. with the risk of "loosing" the last 2 SAS ports when updating.


I was hoping  I could just disable the SATA ports in BIOS, and use just the 8 SAS ports, but I found no option to do so.


Now, my question to the guru's here:

Can I remap the drive order in a config file (and not having it broken during updates) and keep my 8 SAS ports as drive 1-8?

(and maybe use 4 of the 6 SATA ports if needed)


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Well, I mounted synoboot in shell and used "vi" to edit grub.cfg


The related line there now reads:


set sata_args='sata_uid=1 sata_pcislot=5 synoboot_satadom=1 DiskIdxMap=0800 SataPortMap=1 SasIdxMap=0'


And after a reboot, with making no HW changes, I still get this:


The first drive is connected to the first SATA port, the next 3 are connected to the first 3 SAS ports.

This is the same enumeration as I had before editing grub.cfg,

would I need to delete/remove Volume/Pool to see a change?

Edited by bearcat
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What was DiskIdxMap before (did it exist)?  If that is the way it is now, try DiskIdxMap=0008


Here's the text from the Kconfig:


Add boot argument DiskIdxMap to modify disk name sequence. Each

two characters define the start disk index of the sata host. This

argument is a hex string and is related with SataPortMap.

For example, DiskIdxMap=030600 means the disk name of the first

host start from sdd, the second host start from sdq, and the third

host start sda.

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New day, fresh start ;-)


The startingpoint was a default(?) value of DiskIdxMap=0C 

Then I changed it to 0800, and now I tried 0008 with the same result, no visable change in the disk layout.


Off to rethink ... 


DS3615xs, DSM 6.2.3-25426 Update 2.

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So, just for the heck of it ... 

I can not disable the SATA ports in the BIOS, but I'm allowed to change status from AHCI to either RAID or IDE, 

so I tested with IDE, as I know that is not supported, and that was "working" as I expected.

(did not bother to change the last value, still at 0C0800)



The total of 14, is the result of a modification of the original 12.


I can sort of live with this,

going back to the max 12, and disable SATA by forcing them to run as IDE, will give me a stable 8 SAS ports.


But, as I'm curious as of what/why/how

(and I might need some of the extra 6 SATA ports, even if they are slower)

it would be nice to get a better understanding of this problem.



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  • 2 weeks later...

Is it just me or do folks seem to under estimate the speed of sata ports?

Even at sata2 speeds with room for overhead, easily push 300MB/s

Even the fastest sata mechanical drives don’t achieve that speed, close but not quite yet. 

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@merve04 No, I do not underestimate the speed of the ports,

but I think you missed the point as to why I was asking for this in the first place.


A default install of 3615/3617 will give a total of 12 usable drives, that can be bypassed by editing 2 files.

The "bypass" may be overwritten during an update, and that will cause a problem with any Volume/Raid group that uses the "extra" drives.


So, by using the 6*SATA + 8*SAS ports, I get a total of 14 drives in my pool, and I have to "risk" loosing the last 2*SAS ports, when starting the count with the Sata ports.

If I could start with the 8*SAS ports, adding them to Volume1, they will stay safe if this happens.

I could then use the 6*Sata ports, adding 4 to Volume2, and the last 2 for Volume3, where any temporary/non critical stuff could stay.

In case my config gets "updated", back to default 12 drives, I can restore my settings, and recover my Volumes and data, no problem.


btw.: It's not all about bandwith = MB/s, but IOPS and SAS is better there as well. 

Don't forget that SAS is full duplex, where SATA is half duplex, adding "bragging points" to SAS, when data is flowing both ways.

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