Interpreting stickers on RAM

hardwarememory

Does anyone know how to read the labels on RAM? Or have a link to a good resource for reading the labels?

Here's why I'm asking:

I have a third-party Dell server in my rack. The vendor sent us additional memory to install, but it doesn't work. The single stick already installed says PC3-10600E and the one they sent me says PC3-10600U. The *U one does not work, even by itself. I'm trying to figure out the difference between *E and *U.

Best Answer

It's the difference between ECC, Registered and Unbuffered RAM. (E, R, U)

You want more of the "E" RAM if that's what was there in the first place. Typically, they do not mix. The server should have RAM and DIMM population guidelines listed on the chassis cover.

Also see: HP DL160 G6 memory PC3-10600R vs PC3-10600E

Related Solutions

Linux – CentOS server. What does it mean when the total used RAM does not equal the sum of RES

The "used" field in top reflects the total amount of RAM being used, including that by processes, file buffers, and cache. But the RES number shows only the amount of RAM being used by a process, exclusive of the file buffers.

To really see how much RAM is being used without the buffers, use the free command and look at the -/+ buffers/cache line. The number in the "used" column shows how much RAM is actually being used by processes.

Here's an example:

$ free
             total       used       free     shared    buffers     cached
Mem:       2057196    1812352     244844          0     344768     833660
-/+ buffers/cache:     633924    1423272
Swap:      2097148          0    2097148

This output shows that the system has 2GB of RAM, of which 1.8GB is being used. However, 344MB of that is used by buffers and 833MB is used by cache. Subtracting that out leaves only 633MB being used by processes and kernel.

Run the free command before and after launching your Java app to get a better idea of what's going on.

Edit: removed references to the kernel memory, which is not reported by these tools.

Dell PowerEdge – Advanced ECC vs Optimized for 8GB RAM

So as per the comments above and some extra info, I think this is the fastest configuration:

RDIMM (see page 8 'High Performance')
3 x 1Gb (or 3 x 2Gb) sticks per CPU (see page 8 'High Performance')

I realize these options won't provide exactly 8Gb RAM, but that amount appears to be an inefficient one for this processor type. Multiples of 3 seem to be the most appropriate.

Best Answer

Related Solutions

Linux – CentOS server. What does it mean when the total used RAM does not equal the sum of RES

Dell PowerEdge – Advanced ECC vs Optimized for 8GB RAM

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