Re: Disk I/O slowness

On 7/29/26 19:01, Casey Deccio wrote:
> 
>> On Jul 29, 2026, at 6:51 PM, David Christensen <[email protected]> wrote:
>>
>> What is the model number/ part number of your motherboard?
> 
> MBD-X12DPI-N6-O


That looks like a nice motherboard:

https://www.supermicro.com/en/products/motherboard/X12DPi-N6


>> Have you disabled Intel PCH RAID in Setup -- e.g. so that the motherboard disk interface ports appear as non-RAID ports (SATA/SAS)?
> 
> No, I haven't tried that.


I expect Intel PCH RAID is turned off, or you would not see all three 
disks.  But, it would be good to double check.


>> How are the disk drives connected to the motherboard?  What is the speed rating of the cables?  Do the cables have locking connectors?  If you are using backplanes/ racks, what is their speed rating?
> 
> Thanks.  These are all good questions.  I don't have the cable specs or speed ratings on hand (and won't be able to check them for a few days, unfortunately), but they are the cables that came with the motherboard.  


The motherboard has "14 SATA3 (6 Gbps)" ports and I expect the included 
cables will match.  I just wanted to make sure that you were not using 
leftover cables that could be 3 Gbps or 1.5 Gbps (been there, done that, 
hated it).


For single SATA cables, I do prefer locking cables -- to prevent 
accidental disconnects when I am working inside the case.  These cables 
are also marked "6 Gbps", so I can verify in the future:

https://www.cablematters.com/pc-187-156-3-pack-straight-60-gbps-sata-iii-cable.aspx

https://www.cablematters.com/pc-188-156-cable-matters-3-pack-90-degree-right-angle-60-gbps-sata-iii-cable-18-inches.aspx


> In the mean time, I'll try some of the other tests that you (and others) have kindly suggested.
> 
> As a point of reference, however, I built another machine with the same drives and cables (different motherboard), and I haven't experienced these issues.


If that motherboard is more recent than Debian Stable, the included 
Linux kernel might not support the C621A chipset and/or other chips on 
the board.  Please check if the Linux kernel in Debian 13.6 has support 
for the Intel C621A chipset.  Also check if there are bug reports for 
that combination.  If support is lacking, or if there are issues, you 
might need a newer kernel from backports or you might need to run Testing.


Does dmesg(1) report any error messages during transfers?


>> Have you run SMART long tests on each of the three disk drives in the RAID5?  If not, please do so now.  Please post the extended reports from the top through and including the end of the section "SMART Attributes Data Structure revision number: ...".
> 
> I've started the SMART long tests on the three drives in the RAID5.  It will take a few hours to run, so I'll report back.


Okay.


>> How are you transferring files?  Please post your console session.
> 
>  From a different machine:
> 
> $ sudo rsync -av /home/someuser root@newmachine:/home/


Rather than timing sync(1) commands on the destination machine, add the 
--progress option to rsync(1) on the source machine.  Alternatively, add 
the --verbose option.  Understand that rsync(1) is doing a lot of work 
behind the scenes and that network traffic can slow down, speed up, 
pause, etc., over the course of a transfer.


> Thank you!
> Casey


YW.


David