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I have an old laptop that I have retasked as a file server (running on debian with a samba server), and have recently decided to upgrade the RAM from 1GB to 2GB. Before I had upgraded the RAM, when I ram free, it was saying that approximately 99% of the RAM was in use right after boot, but now, after the upgrade to 2GB, it is saying 12.5% after boot, almost a quarter of what was initially being used at that point. The main difference between the original ram and the new ram (apart from the capacity) was the speed, originally 553, now 667. Can anyone tell me what would have changed so much within the system that would have caused such a drastic change in memory usage?

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How precisely are you measuring RAM "usage"? Which field in free are we talking about? – David Schwartz Mar 6 '13 at 1:05
@DavidSchwartz What was in the used column of the mem row – topherg Mar 6 '13 at 1:06
Perhaps some of the ram is allocated to on-board graphics and rendered unavailable to the rest of the system at boot? – washbow Mar 6 '13 at 1:06
@washbow The system is set up to only run in terminal mode, no desktop or anything. I was connecting to it over SSH – topherg Mar 6 '13 at 1:07
I believe it would be allocated by the bios, and so it wouldn't matter what the actual usage was. Is there such a feature on this laptop? – washbow Mar 6 '13 at 1:10

Most likely, there was a lot more disk I/O the first time, resulting in more memory being used as a disk cache. This could have been caused by any number of things, but the most likely is the fsck process ran on the first boot and not the second. This reads lots of filesystem metadata which will stay in memory if the OS has no reason to remove it.

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I see where your coming from, but it would do it constantly during its time with 1GB. It had been like that for well over 3 months with absolutely no change over up-time, or number of reboots – topherg Mar 6 '13 at 1:14

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