iSCSI throughput IO not as fast as expected [synology noob]

[XxUnkn0wnxX]

Hi, I just recently got a DS1821+ i'm very new to Synolgy, I've been with Drobo for more than 10 years however since they went under I needed to find a new product that supported hybrid raid with a close match to a DAS setup as possible. I have set up ATTO ISCSI Initiator on my Mac and the Lun's on the Synology however I'm only getting about 110MBps read & write compared to my Drobo's 300MBps read & write. I do have SSD caching on there as well as the Synology.

Current hardware Setup for Synology:
32 gigs of ram
2TB NVME Cache X1 (read only), will put in a 2nd one soon for write as well.
Seagate 16TB Exo [ST16000NM001G] Enterprise Drives X3

Drobo has the same model HDD's as well.

now I have messed around with MTU with varying success, I either get faster write but read takes a big hit or vise versa..
I have also tested 2 network nodes instead of the 1 via the ISCSI Initiator. so Link Aggregation more less via 2 network cables & read & write does hit around 170MBs but is still very slow compared to Drobo's speeds.

I Have Stripe Cache size set to small for better IO

also, the storage pools are still optimising in the background not sure if this affects anything..

also, no data has been transferred yet as I want to get this IO issue resolved first..

also I ran iperf command

[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.00 sec  1.09 GBytes   940 Mbits/sec

and no issues on the network side of things.

I'm also using Blackmagic Disk Speed Test to test the IO speed.

so I'm not sure what to do here, its like the SSD cache is not being utilised first for all new disk write/read operations..
is there anything i can tweak so it uses the cache first rather than writing to disk?

or do i need to wait till the storage pools are done optimising?

because with Drobo it uses the SSD cache first & when it fills up it then slows down IO till the SSD cache offloads to the main storage array, I would have assumed Synology does this as well?

 

[strikes2k]

Well, that model only has 1 Gbit NICs built in so 940 Mbits/sec is pretty good. It's almost maxed out and would reasonable translate to about 110 MBps. What kind of networking did your Drobo have? I know one of the knocks on Synology has been that their competitors have embraced 2.5 Gbit networking while Synology has not. If extra performance is important to you you might want to consider a 10 Gbit NIC in the PCI slot if the rest of your network supports 10 Gig.

 

[XxUnkn0wnxX]

Well, that model only has 1 Gbit NICs built in so 940 Mbits/sec is pretty good. It's almost maxed out and would reasonable translate to about 110 MBps. What kind of networking did your Drobo have? I know one of the knocks on Synology has been that their competitors have embraced 2.5 Gbit networking while Synology has not. If extra performance is important to you you might want to consider a 10 Gbit NIC in the PCI slot if the rest of your network supports 10 Gig.

mine was via Thunderbolt connection so it wasn't a NAS

& now that I think about it 125 MBps is probs max..
ya 1 Gbit Nic adaptor won't cut it.

I think my math was wrong earlier, was thinking Gbit = 1000MBps speeds

 

[Rusty]

The only way to get "DAS" speeds with a NAS is with a faster interface. 1821 has the option to go 10G and that will give you a 1GB/s transfer if your client side can support it. You an also connect to the client directly in this way to utilize the speed with no need of getting a 10G switch.