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February 22nd, 2025 02:31

RAID Controller Misidentifying SSDs as Rotational on Server

If there's a RAID expert here, we would appreciate your assistance with the following.

We are experiencing an issue with our server Dell PowerEdge R630 running RAID 10 on PERC H730 Mini RAID controller with Ubuntu 22 Lts. 
Our recent performance tests using FIFO commands show read speeds of 2700 MB/s and write speeds of 1800 MB/s, which are lower than expected for our RAID-10 setup.  

Upon investigation, we found that the Dell PERC H730 Mini RAID controller (Broadcom MegaRAID SAS-3 3108) is incorrectly detecting our SATA SSDs (Micron 5210) as rotational devices (ROTA=1) instead of non-rotational (ROTA=0). This misclassification can lead to suboptimal I/O scheduling, affecting overall performance.  


The output of lsblk -o NAME,ROTA,DISC-MAX


So on recommendations we added a file 

/etc/udev/rules.d/99-non-rotational.rules


Added the content


ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-ubuntu--lv", ATTR{queue/rotational}="0"

ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-lv--kvmdata", ATTR{queue/rotational}="0"
ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-vsv1017--dn4S8Q51DQNaT7fg--3bRpfjxjIRtCg5r3", ATTR{queue/rotational}="0"
ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-vsv1018--dejnhTUJQifyOUDT--tKQdhCLEotCGP7mz", ATTR{queue/rotational}="0"
ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-vsv1019--dPSXM0StizWx1RB5--vZ58gXA2ryO3ksqQ", ATTR{queue/rotational}="0"
ACTION=="add|change", ENV{DM_NAME}=="ubuntu--vg-vsv1027--d4HiXQkMj1CoCoIZ--AU8xHN14C7U9vYkA", ATTR{queue/rotational}="0"
ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}="0"


executed the command


udevadm control --reload-rules

udevadm trigger
update-initramfs -u  # So that the setting remain intact on reboot


The output of lsblk -o NAME,ROTA,DISC-MAX after the changes


And the speed test results

fio --name=mixed_rw50 --ioengine=libaio --rw=randrw --rwmixread=50 --bs=4k --numjobs=4 --size=1G --runtime=60 --group_reporting --filename=/tmp/fio_test

mixed_rw50: (g=0): rw=randrw, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=1
...
fio-3.28
Starting 4 processes
Jobs: 4 (f=4): [m(4)][64.3%][r=402MiB/s,w=403MiB/s][r=103k,w=103k IOPS][eta 00m:05s]    
mixed_rw50: (groupid=0, jobs=4): err= 0: pid=3142982: Sat Feb 22 07:55:55 2025
  read: IOPS=54.2k, BW=212MiB/s (222MB/s)(2046MiB/9659msec)
    slat (nsec): min=1546, max=8143.4k, avg=59369.06, stdev=121660.94
    clat (nsec): min=747, max=1128.5k, avg=1361.98, stdev=2555.22
     lat (usec): min=2, max=8150, avg=60.91, stdev=122.25
    clat percentiles (nsec):
     |  1.00th=[  764],  5.00th=[  932], 10.00th=[  932], 20.00th=[  940],
     | 30.00th=[  948], 40.00th=[  956], 50.00th=[  980], 60.00th=[ 1256],
     | 70.00th=[ 1400], 80.00th=[ 1576], 90.00th=[ 2256], 95.00th=[ 2800],
     | 99.00th=[ 4048], 99.50th=[ 5088], 99.90th=[11072], 99.95th=[13632],
     | 99.99th=[19584]
   bw (  KiB/s): min=25328, max=962488, per=93.04%, avg=201791.53, stdev=55412.08, samples=76
   iops        : min= 6332, max=240622, avg=50447.68, stdev=13853.02, samples=76
  write: IOPS=54.3k, BW=212MiB/s (223MB/s)(2050MiB/9659msec); 0 zone resets
    slat (nsec): min=1949, max=2050.3k, avg=8387.45, stdev=39394.09
    clat (nsec): min=751, max=1162.7k, avg=1130.97, stdev=1715.29
     lat (usec): min=2, max=2054, avg= 9.64, stdev=39.52
    clat percentiles (nsec):
     |  1.00th=[  764],  5.00th=[  812], 10.00th=[  940], 20.00th=[  940],
     | 30.00th=[  948], 40.00th=[  956], 50.00th=[  964], 60.00th=[  988],
     | 70.00th=[ 1064], 80.00th=[ 1336], 90.00th=[ 1464], 95.00th=[ 1656],
     | 99.00th=[ 2768], 99.50th=[ 3312], 99.90th=[ 9408], 99.95th=[12096],
     | 99.99th=[17792]
   bw (  KiB/s): min=26480, max=966720, per=92.97%, avg=202056.89, stdev=55586.49, samples=76
   iops        : min= 6620, max=241680, avg=50514.05, stdev=13896.64, samples=76
  lat (nsec)   : 750=0.01%, 1000=57.62%
  lat (usec)   : 2=34.98%, 4=6.70%, 10=0.59%, 20=0.10%, 50=0.01%
  lat (usec)   : 100=0.01%, 250=0.01%, 1000=0.01%
  lat (msec)   : 2=0.01%
  cpu          : usr=7.05%, sys=24.70%, ctx=131511, majf=0, minf=177
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued rwts: total=523742,524834,0,0 short=0,0,0,0 dropped=0,0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=1

Run status group 0 (all jobs):
   READ: bw=212MiB/s (222MB/s), 212MiB/s-212MiB/s (222MB/s-222MB/s), io=2046MiB (2145MB), run=9659-9659msec
  WRITE: bw=212MiB/s (223MB/s), 212MiB/s-212MiB/s (223MB/s-223MB/s), io=2050MiB (2150MB), run=9659-9659msec


We would appreciate help from anyone who has encountered this issue and found a workaround to improve performance, which we believe can reach up to 6GBps to 7GBps.

Thank you in advance!

Moderator

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5.1K Posts

February 24th, 2025 01:38

Hello, thanks for choosing Dell.

I believe this is more for the consulting realm than troubleshooting that us tech support offer.

What I see is that SATA SSDs (Micron 5210)  -> I don’t think this is a Dell part

This read may help:

https://dell.to/4gWYDwm

 

You could try tweaking Read Policy to No-Read-Ahead.

 

Respectfully,

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