iSCSI advices / Best practices

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Foussa
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iSCSI advices / Best practices

Unread post by Foussa » Thu Apr 27, 2017 10:51 am

Hello there,

As a NAS noob, I'd like some advices / best practices on my R816 iSCSI configuration.
I'm going to host VMs with proxmox and to store the VMs on my synology using iSCSI block level.

Furthermore, I'd like to mount shares of my synology on the VMs.

Is it possible?
If yes, what is the best practices to implement this configuration?

Thanks in advance.

synology_ukman
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Re: iSCSI advices / Best practices

Unread post by synology_ukman » Fri Apr 28, 2017 4:59 pm

Don't expect much performance.
read
https://www.synology.com/en-uk/knowledg ... nology_NAS

CueBall909
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Re: iSCSI advices / Best practices

Unread post by CueBall909 » Fri Dec 15, 2017 8:29 pm

How much performance should we expect? Your link doesn't give any performance info and the Wiki appears to be offline.

I've got a DS3612xs that I have been using as a Veeam backup repository for the last year and a half. Performance has always been poor, no matter how I configure MPIO or the iSCSI connections. I thought perhaps the network connections were the bottleneck, so I upgraded my server and the Synology to 10GbE (direct connected with no switch). I'm still only seeing ~110-120 MB/sec read/write (sequential). That's only slightly better than I was getting through a single 1GbE connection. Sustained read IOPS are in the 200 range. Write IOPS get as high as 800, but still only gives ~110-120 MB/sec.

The LUNs are block level running on SHR/1 disk groups. One LUN uses 12 disks (WD Red), so I shouldn't be disk/spindle limited. I've tried setting MTU=9000 on both ends, but that gave no increase in throughput. LUNs are formatted using NTFS and are attached to a Windows Server 2016 machine with tons of CPU and RAM.

I'm stumped as to why performance is so bad on the current setup. I expected to easily get 180MB/sec out of this setup and I'm nowhere close.

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Re: iSCSI advices / Best practices

Unread post by CueBall909 » Mon Dec 18, 2017 6:26 pm

Replying to my own last post.

I've been able to dramatically increase my throughput. The problem was the system constantly trying to connect over the non-10GbE connection. I configured the firewall on the Synology to block connections from my backup server over that NIC and only allow connections through the 10GbE NIC. I'm now getting over 300MB/sec reads and over 250MB/sec writes (sequential, using CrystalDiskMark). So, it's possible to get great throughput as long as the configuration is correct and you're using 10GbE. However, I tried just about everything when using 1GbE and could never break 120MB/sec, even when using multiple connections and MPIO.

I think that if I can reformat my LUNs using larger blocks, ReFS, and more disks I'll be able to get even better performance.

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