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[Solved] Any idea why those two drives are dramatically slower than the rest? (feddit.org)
submitted 4 days ago* (last edited 4 days ago) by to c/selfhosted@lemmy.world
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I have eight identical drives connected to an LSI 9207-8i ASRock X470 Taichi Ultimate mainboard.

They're currently all running badblocks -b 8192 -c 2048 -p 0 -s -t 0 -v -w /dev/disk/by-id/ata-WDC_WUH722424ALE6L4_[XXXXXXXX] each.

While sda and sdb achieve almost 300MB/s, sdg and sdh struggle to even get to 200MB/s. That's a 50% difference!

All of my drives are recognized as SATA3, confirmed by smartctl -a /dev/sd[a-h] | grep SATA showing SATA Version is: SATA 3.5, 6.0 Gb/s (current: 6.0 Gb/s)

There's no CPU bottleneck either AFAICT:

Any idea what could be the issue of that? Is such a dramatic speed difference to be expected of Ultrastar drives?
Are these drives just bad?

Edit: Mainboard configuration:

Edit2: Okay, apparently the ASM1061 which provides the two extra SATA3 ports is connected to the CPU via a single PCIe 2.0 x1 lane, which provides only 4gbps (=500MB/s) of raw throughput.
I think I have found the culprit and the problem should disappear once I connect the drives to my LSI 9207-8i HBA card.

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[–] 3 points 4 days ago

It's one of the reasons why getting a SAS controller is really nice, backplanes make it even better.

I was preforming a burn with 10 X 8TB drives on a controller that already had a couple operating ZFS pools totaling 18 X 4TB drives and a couple SSD's and there was no slow downs. A SAS3008 controller can support over 6000 MB/s and has a PCI Express X8 3.0 bus.

I've been building my servers and network out of old enterprise gear for a while now. It uses more power but the things you can do are truly amazing. Sadly the ai boom drove prices way up compared to a couple years ago, what I bought for 900 in 2024 is running around 1500 today.

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