iSCSI slow

iSCSI related applications
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RcTomcat
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Posts: 31
Joined: Tue Feb 22, 2011 3:19 am

iSCSI slow

Post by RcTomcat » Sat Dec 26, 2020 4:34 am

Hi Guys,

I got the following Setup:

2 iSCSI Luns connected to a Windows 10 Machine.
One via a 10Gbit Connection on a 251D with an SSD Cache, the other from a 463 via 1Gbit also with an SSD Cache.
Both LUNs have a an NTFS Volume on it, allowing for a mere 200-220Mbit/s (max 25Mb/s) of Transfer Speed on Write. Response time is about 250ms, Active time max 50%. Read seems fine.
The iSCSI LUNs seem to have the same slow write speed no matter if SSD Cache is enabled or disabled.
Source for writes is an NVMe SSD, which should be capable of maxing out that 10G Network Connection or at least the SSD Cache on the NAS.

Any Idea what might be the issue here? I can write to both NAS via SMB with full Gbit Speed.

deathmage85
Starting out
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Joined: Thu May 06, 2021 12:24 pm

Re: iSCSI slow

Post by deathmage85 » Thu May 13, 2021 11:31 am

your limitation is the Windows 10 network stack. Get a 10G nics for your Windows 10 machine and a cheap 10G switch and try it again. Also, you have a QM2 card, check to see how much QNAP memory you have to the ratio of QM2 SSD caching; if its out of sync that's not helping things. Also checking your existing switch, the local switching cache might be your limitation.
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Lab:
(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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