Slow speeds using iSCSI LUN

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Slow speeds using iSCSI LUN

Post by SmelliotButton » Fri Mar 19, 2021 5:27 am


After looking through the forums I couldn't really see anything similar to my issue - apologies if I missed something!

I have a QNAP TS-469U with four WD 3TB Red drives running in RAID 10. I then have a VMware ESXi 7 running a few Windows Server 2019 virtual machines. Linking the two is a HP 1810-24G switch and CAT5e cables.
The two 1Gbps Ethernet ports on the QNAP are setup with Port Trunking, running IEEE 802.3ad. I have made sure that the HP switch supports 802.3ad. Jumbo Packets have been enabled on the QNAP NAS and the Switch.

As an example, when copying a 13GB .zip file from my local machine (SSD drive) to a shared folder on one of the virtual machines, I get a steady 100MB/s copy speed (although the virtual machine is running on an SSD drive connected directly to the VMware ESXi host). This test was more to rule out any issues with the switch.
When copying the same file to a LUN hosted on the QNAP NAS, the copy firstly starts at around 1.3GB/s but then drops down to around 60MB/s quite quickly and continues at that speed for the remaining copy time.

The fact that copy starts above 1GB/s makes it seem that the NAS is capable of that transfer speed, but something is then slowing it down. I am aware that the logical transfer speed would never be possible, but am I right in thinking that I should be getting a maximum of 250MB/s? Due to two WD Red drives running at 140MB/s each and them running in RAID 0, and then the Port Trunking ports on the switch running at 250MB/s total?

Sorry if this seems like a jumbled wall of text! If there is anything I need to check or clarify to help please let me know.

Thanks in advance!

Just to confirm, the QNAP NAS is running the latest firmware of V4.3.4.1463 (2020/10/06). The firmware is also up to date on the HP switch.

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Re: Slow speeds using iSCSI LUN

Post by dolbyman » Fri Mar 19, 2021 10:52 am

checked a couple of reviews from when that atom unit was new(2013) ..all have it hover under 100MB/s max.(read/write) Trunking would also only improve transfers from multiple systems

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Re: Slow speeds using iSCSI LUN

Post by SmelliotButton » Tue Mar 23, 2021 9:09 pm

Hi dolbyman,

Thanks for your response and sorry for the delay in mine!

I've confirmed that I have Port Trunking enabled on the NAS using both Ethernet ports and IEEE 802.3ad. Is there anything else I can check?


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Re: Slow speeds using iSCSI LUN

Post by deathmage85 » Thu May 13, 2021 11:44 am

This sounds like a disk caching issue on the NAS. Can your QNAP support a QM2 card?

also copying from your local PC to the QNAP is all limited by the bus speed of your wireless card or LAN card buffer cache as it tied into the Windows network stack as it moves the data along the wire. You'll never get true gigabit speeds on a Windows 10 machine as an example.

Also, check your 1810, that switch may not have a high switching cache on the switch if it's really low, it might start out fast then get slower and that's the cause of the switch cache.

as mentioned it's cache in one leg along the chain someplace.

For example, I have a TS-832X with 10G enabled into a 10G Cisco switch into a 10G X710 DA2 card with jumbo frames enabled with the QNAP having a QM2 card for r/w caching and I'm nearly at a line rate speed of 10G in ESXi 7.0; the entire chain is built from end-to-end to sustain the speed
Sr. System Administrator
Certifications: Microsoft Certified Solutions Expert x 3 (Core Infrastructure, Security, & Productivity), Microsoft Certified Azure Administrator & Office 365 Messaging Administrator, VMware VCP 5 & 6 DCV/NV, VMware vExpert 2015-2021, CompTIA: A+, Network+, Storage+, Server+, Security+, Cybersecurity Analyst+ (CySA+), and Certified Advanced Security Practioner (CASP+)

(1) TS-832X - (Hybrid) - (4) 8 TB WD Red Pro in RAID 10, (4) WD Blue 1 TB SSD's in RAID 5 - QM2 Dual M.2 SSD card

(1) TS-832X - (All-Flash) - (8) 1 TB WD Blue SSD's in RAID 5 - QM2 Dual M.2 SSD card

(2) TS-230 - (2) 6 TB's RAID 1 - Backup repository for Veeam BR 9.5

(1) TS-453D - (4) 6 TB's in RAID 6 - File Server with QM2 Dual M.2 SSD card

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