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M.2 PCI Adapter


Vodka2014
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Hi All,

 

So I have been looking and I see that if the M.2 is on the Motherboard it can only be used and Read OR Read-Write Cache and not as a Storage Device to use like a Normal SSD or HDD.

 

If i get a PCI-E Adapter with 2 / 4 M.2's on them will this work for 918+ Or what is recommended OR if somehow I can use the M.2 Other then Cache. 

 

Thanks in advanced. 

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M.2 is a multi purpose interface, and its implementation is dependent upon the motherboard or host card. Some or all of the following may be true:

  • Most people think of M.2 as an interface to a NVMe SSD, but in reality the NVMe card is a PCIe device.  In that respect, it's a PCIe slot in a different form.
  • A NVMe SSD is simply a PCIe device that fits into the M.2 slot form factor.
  • The M.2 slot can also be mapped to a M.2 SATA SSD and internally connected over the same edge connector to a SATA HBA.

Assuming it is supported by the motherboard or card, an M.2 SATA SSD should work fine with DSM as it is seen as a SATA device.

 

A PCIe adapter with multiple M.2 slots is simply a PCIe switch or bifurcator.  For what it's worth, you can buy M.2 to PCIe adapters as well.

 

You already know that a M.2 NVMe SSD cannot be natively used by DSM as regular disk, just as cache (with patch).  Your best functional option to use NVMe with DSM is to install DSM within a hypervisor (ESXi), which can then virtualize and syndicate the NVMe storage to DSM as a VMDK (virtual disk image) or RDM (raw device mapping).  RDM is preferable as it performs better, gives you 100% of the space and the device can be directly attached to a virtual SATA controller so it appears as SATA to DSM.

Edited by flyride
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Read up a little on hypervisors.  ESXi, ProxMox VE, KVM, XenServer, etc are all hypervisors, which run as the initial boot environment (before an operating system).  Hypervisors manage virtual machines, each of which are completely seperate and independent of each other.  DSM is then run as a virtual machine workload within the hypervisor environment.  We can support NVMe services because they are managed completely outside of the DSM VM.

 

DSM has the ability to act as a hypervisor (VMM), but this is not useful to support NVMe drives (since DSM doesn't support them in the first place).

 

Docker is not a hypervisor, it's an aliased environment within Linux.  Docker apps share the same Linux working environment.  You might think of it working in the same way as a hypervisor, but it is quite different.

 

It is possible to import your baremetal XPe DSM system into an ESXi VM, but that is a technically demanding task and you should be very familiar with XPe and running it under ESXi before attempting it.  So yes, you would probably need to plan to "start over" and import your data once everything was set up and tested under ESXi.

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  • 1 month later...
On 1/13/2021 at 10:22 PM, flyride said:

Your best functional option to use NVMe with DSM is to install DSM within a hypervisor (ESXi), which can then virtualize and syndicate the NVMe storage to DSM as a VMDK (virtual disk image) or RDM (raw device mapping).  RDM is preferable as it performs better, gives you 100% of the space and the device can be directly attached to a virtual SATA controller so it appears as SATA to DSM.

 

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  • 11 months later...

I know, almost a year since the last post has been sent…anyway, does anybody know if it’s possible to use a dual m.2  pcie card to get access to approx. 1000Mb/s for caching when using 3615xs instead of dealing with the sata speed?

Edited by TNa681
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1 hour ago, TNa681 said:

…anyway, does anybody know if it’s possible to use a dual m.2  pcie card

NO, yes, yes

 

NO, not in general

 

yes, only if the controller has its own pcie bridge chip (expansive controller)

or

yes, when thy system/bios supports bifurication on a 8 or 16 lane pcie connector

https://peine-braun.net/shop/index.php?route=information/information&information_id=7

 

so most cheap cards like that (4 x nvme on a 16x card) for a low amount of money will need bifurication support, if the card costs 300-500 bugs it might be one with a bridge chip

 

Edited by IG-88
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6 hours ago, TNa681 said:

price and a extra heat sink indicate that it has that extra chip - the price above was rough for a 4 x m.2 card, looks like 2xm.2 is more affordable

also slight correction, the chip is called a pcie multiplexer

 

no chip

ASUS Hyper M.2 x16 Gen 4 (PCIe 4.0/3.0) , 4X NVMe M.2, $40-$60 (similar cards seen for up to $140)

 

with chip

Sonnet M.2 4x4 Silent PCIe Card (FUS-SSD-4X4-E3S), ~$450

A ADWITS Quad M.2 NVMe SSD PCIe X16 Adapter,ASM2824 PCI Express 3.0 X16 Switch to 4 Ports M.2 Adapter Card, ~$300

DeLOCK PCIe -> M.2 PCIe (89961) ~$300

DeLOCK PCIe -> M.2 PCIe (89044)~$300

 

there are other pcie 8x cards for 2 x m.2 like the one you mentioned for around $200

StarTech PCI Express x8 Card > 2 x internal NVMe M.2 Key M (PEX8M2E2)

DeLOCK 2x M.2, PCIe 3.0 x8 (90305)

maybe there are some no name models directly from china for price below $150

 

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  • 2 weeks later...
On 2/16/2022 at 4:55 PM, flyride said:

You keep asking the same question. The answers have been posted in this thread multiple times.

 

Don't agree...think its more like putting a puzzle together and because of that I asked in a different way to hopefully get a clear reply.

 

In my case I'd like to go the easiest way which is to keep my baremtal 3615xs 1.03b -> add two solo pcie to m.2 adapters -> create a raid 1 r/w caching disk.

 

Couldn't find this information clearly within the entire forum and just want to be sure about that before shopping.

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Ok.  I will repackage the information in this thread and hopefully it will be clear.

 

9 hours ago, TNa681 said:

I'd like to go the easiest way which is to keep my baremtal 3615xs 1.03b -> add two solo pcie to m.2 adapters -> create a raid 1 r/w caching disk.

 

DS3615xs does not support native NVMe.  At all.

M.2 is actually PCIe in a small form factor.  All PCIe to M.2 adapter does is link one connector to the other.  It has no ability to make the M.2 device accessible to DS3615xs.

 

The only way I know of to access an NVMe device with DS3615xs is to use a hypervisor to spoof it in as a SATA device - i.e. VMDK or RDM mapping.

I would not recommend using VMDK or RDM mapping for DSM cache but you may find that it works.  Both approaches are used successfully for Storage Pool array devices.

Edited by flyride
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7 hours ago, flyride said:

DS3615xs does not support native NVMe.  At all.

M.2 is actually PCIe in a small form factor.  All PCIe to M.2 adapter does is link one connector to the other.  It has no ability to make the M.2 device accessible to DS3615xs.

 

The only way I know of to access an NVMe device with DS3615xs is to use a hypervisor to spoof it in as a SATA device - i.e. VMDK or RDM mapping.

I would not recommend using VMDK or RDM mapping for DSM cache but you may find that it works.  Both approaches are used successfully for Storage Pool array devices.

yes and no, i added a nvme kernel driver ~5/2020 for 3615/17 to my extra.lzma, so a nvme ssd should be usable but will not be manageable in dsm's gui, in theory making a basic disk or raid set might be possible by fiddling manually

no cache support for dsm i guess, maybe as data volume but manually adding stuff like this will make any update to the system a russian  roulette, even any automatic repair attempt by dsm my result in data loss - nothing i would do, not worth the risk imho

but if someone rsync's all data all the time to a 2nd backup system it might minimize the risk of data loss

 

i would suggest using a hardware thats capable of 918+ or in case of 3615/17 using sata ssd's, even with "only" sata there would still be betetr performance because its 550MB/s and way better iops of ssd

 

edit: systems working with 3615 usually can run 3617 and this one supports synologys M2D20 m.2 nvme adpter with dsm 7.01 so it might be possible to get m.2 nvme working with older (non 918+) hardware in dsm

Edited by IG-88
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1 minute ago, IG-88 said:

yes and no, i added a nvme kernel driver ~5/2020 for 3615/17 to my extra.lzma

 

It's not just kernel support that is missing, but there are a number of NVMe tools that are also part of DSM that are not present on DS3615xs.

 

Interestingly enough, DS3617xs 7.0.1 seems to have native NVMe support, presumably to support the M2D20

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3 minutes ago, flyride said:

Interestingly enough, DS3617xs 7.0.1 seems to have native NVMe support, presumably to support the M2D20

 

after clicking submit i remebered having seen that on synologs's list so i checked that and added a edit, its true, its in syno's list but only with synologys own ssd#s and as we know from 918+ it would need a patch to work with nomal nvme ssd's

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  • 4 weeks later...
On 2/18/2022 at 11:41 PM, flyride said:

 

It's not just kernel support that is missing, but there are a number of NVMe tools that are also part of DSM that are not present on DS3615xs.

 

Interestingly enough, DS3617xs 7.0.1 seems to have native NVMe support, presumably to support the M2D20

 

SD3622xs+ with DSM 7.0.1-42218 running as a Virtual Machine inside ESXi 7.0 has native NVMe support:

 

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