Looking to upgrade the RAM in a DEC740

[OmnomBánhmì]

For the office we got a DEC740 which has 4GB of RAM. Memory usage is around 40%, which is fine. But, the Swap is always around 59%, so several GB worth of swapping at all times.

The datasheet does not mention user-upgradable RAM, but it does mention its DDR4. We have some of that in store, so could in theory just add to or replace the given RAM to e.g. get 8GB. This could reduce wear and tear on the mass storage considerably, I'd think.

Has anyone done this RAM upgrade successfully? Is that possible or encouraged even?

[meyergru]

I would argue that it can easily be replaced. For reference, I have a DEC750 with 8 GByte and according to 'dmidecode', this is:

Code: [Select]

Handle 0x000C, DMI type 17, 40 bytes
Memory Device
        Array Handle: 0x000B
        Error Information Handle: 0x000E
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 8 GB
        Form Factor: DIMM
        Set: None
        Locator: DIMM 0
        Bank Locator: P0 CHANNEL A
        Type: DDR4
        Type Detail: Synchronous Unbuffered (Unregistered)
        Speed: 2667 MT/s
        Manufacturer: Unknown
        Serial Number: XXXXXXXXX
        Asset Tag: Not Specified
        Part Number: TS1GLH64V6BL
        Rank: 1
        Configured Memory Speed: 2400 MT/s
        Minimum Voltage: 1.2 V
        Maximum Voltage: 1.2 V
        Configured Voltage: 1.2 V

So it is only one slot of DDR4 unbuffered UDIMM which must support at least 2400 MT/s. The Transcend part in my box has CL19 and single rank. It can be, but does not have to be ECC, but it needs to be UDIMM, not RDIMM: https://www.reddit.com/r/OPNsenseFirewall/comments/qxo7eh/anyone_has_info_on_the_a10gen3_board_and_the/

The netboard A10 can support up to 32 GByte: https://www.deciso.com/netboard-a10-gen3/, but to fit into the case, I think you need VLP form factor, such as MTA18ADF4G72AZ-2G6.

You will obviously lose the warranty when you open the device, there is a seal you would have to break.

[Solaris17]

I would argue that it can easily be replaced. For reference, I have a DEC750 with 8 GByte and according to 'dmidecode', this is:

Code: [Select]

Handle 0x000C, DMI type 17, 40 bytes
Memory Device
        Array Handle: 0x000B
        Error Information Handle: 0x000E
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 8 GB
        Form Factor: DIMM
        Set: None
        Locator: DIMM 0
        Bank Locator: P0 CHANNEL A
        Type: DDR4
        Type Detail: Synchronous Unbuffered (Unregistered)
        Speed: 2667 MT/s
        Manufacturer: Unknown
        Serial Number: XXXXXXXXX
        Asset Tag: Not Specified
        Part Number: TS1GLH64V6BL
        Rank: 1
        Configured Memory Speed: 2400 MT/s
        Minimum Voltage: 1.2 V
        Maximum Voltage: 1.2 V
        Configured Voltage: 1.2 V

So it is only one slot of DDR4 unbuffered UDIMM which must support at least 2400 MT/s. The Transcend part in my box has CL19 and single rank. It can be, but does not have to be ECC, but it needs to be UDIMM, not RDIMM: https://www.reddit.com/r/OPNsenseFirewall/comments/qxo7eh/anyone_has_info_on_the_a10gen3_board_and_the/

The netboard A10 can support up to 32 GByte: https://www.deciso.com/netboard-a10-gen3/, but to fit into the case, I think you need VLP form factor, such as MTA18ADF4G72AZ-2G6.

You will obviously lose the warranty when you open the device, there is a seal you would have to break.

^^ This. As long as the ram is a VLP (1.2v) DDR4 UDIMM and is JDEC between 2400/2666 it should work.

At current I have the following 16GB Micron stick (Crucial)

Micron PN: MTA18ADF2G72AZ-2G6E1ZI
Crucial PN: CT16G4XFD8266.18FE1

It works fine in my DEC740.

The following 32gb Micron stick also works.

Micron PN: MTA18ADF4G72AZ-2G6B2

[meyergru]

Then you will have a DEC770 - I only have a DEC760. 

BTW: In case you are wondering about what to do with that amount of memory: Junicast has a YouTube video showing how he installed Proxmox on an upgraded DEC740 with a terabyte of NVME.

[Solaris17]

hah thats a good Idea! I put a 256gb in it that I had around but I know there are a few sales on 1tb at the moment!

[Solaris17]

Updated the previous post. All part numbers and modules were tested personally. You can also look for ones with similar part/model numbers as long as they meet the specified requirements posted previously.

The default BIOS setting for timings and ram clocks is <Auto> so it is simply reading the JDEC rating of the ram installed.

[feld]

> But, the Swap is always around 59%, so several GB worth of swapping at all times.

This only means this data is being stored in swap because it's not being actively used. This does not mean there's a performance issue. You should only worry if you see a lot of page in / page out activity. That would indicate that the memory in swap is being used during normal operations because everything required for the current process is not able to fit into memory.

Keep in mind that FreeBSD's swap behavior is different than Linux.

Let your system use 100% of the swap if it wants to. This is just the kernel optimizing memory for other applications that are making large allocations. Only worry when you see excessive paging.

[OmnomBánhmì]

Thank you all for the detailed replies! I'll check with page in / page out activity, however I do suspect I let myself be fooled by being more familiar with Linux, so may not rush towards upgrading.