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[Solved] Any idea why those two drives are dramatically slower than the rest? (feddit.org)

submitted 1 week ago* (last edited 1 week ago) by Lemmchen@feddit.org to c/selfhosted@lemmy.world

8 comments fedilink hide all child comments

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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[–] cabillaud@lemmy.world 1 points 1 week ago* (last edited 1 week ago) (1 children)

What are "d/s" and "f/s"?

E: I rtfm and.... It's discard requests and flush requests

[–] Lemmchen@feddit.org 1 points 1 week ago* (last edited 1 week ago)

I actually needed to look that up, since I didn't know either. So, thank you, I've learned something new because of your question.

          d/s    The number (after merges) of discard requests
                 completed per second for the device.

          f/s    The number (after merges) of flush requests
                 completed per second for the device.  This counts
                 flush requests executed by disks. Flush requests are
                 not tracked for partitions.  Before being merged,
                 flush operations are counted as writes.

https://man7.org/linux/man-pages/man1/iostat.1.html

(Discards being TRIM operations on SSDs, I imagine.)