Re: to lvm or not lvm is my dillema

Although "swap" became a misnomer once systems moved from "swapping" to
"paging" setting up swap spaces is still an important factor on high memory
systems.   While it is true swap size no longer has to match physical memory
size (at least on Linux) it is also true that swap should be examined and
possibly adjusted as one adds physical memory.

Of course newer tuning settings such as "swapiness" are also important to
examine and set.   

Also, creating multiple equal size swap "devices" (LVs or partitions) is
important as "paging" is done in a round robin fashion if tuned properly.


-----Original Message-----
From: Ale <[email protected]> On Behalf Of DJPfulio--- via Ale
Sent: Sunday, January 4, 2026 10:12 AM
To: [email protected]
Cc: DJPfulio-/[email protected]
Subject: Re: [ale] to lvm or not lvm is my dillema

On 1/3/26 19:13, Steve Litt via Ale wrote:
>> No.   If you increase physical RAM you often want to add SWAP
>> devices.

I disagree.

Since around 2000, the old rules of 2-3x RAM for swap just don't apply if
you want a responsive server.
In the days of more than 4GB of RAM, swap use has drastically changed

a) from "provide virtual memory"
b) to "let the admin know when slowdowns are happening so steps can be
taken".

I try to run my servers without needing any swap, though the kernel setup
prefers _some_ swap to enable performance features.  For the last 2+
decades, I've never added more than 4GB swap to any system, including
desktops.  Only desktops that are hibernated could need more.  For a long
time, I ran servers with ZERO swap. I'd just size the RAM for the VM to be
sufficient for the workload. This worked for almost a decade, but was
probably a mistake. I don't recall when, but the kernel guys enable certain
performance toggles only if there's some swap, so 500M is what I started
adding to servers that really don't need any, but the kernel switches
require. I still try to ensure workloads fit within the RAM only and turn
down swappiness to minimal levels in the tuning.

I'm assuming people can buy more RAM as needed for the workload.  That's
been my experience regardless of workload for multiple decades - both for
servers and desktops.  Laptops aren't desktops. They have a bunch of other
issues, often which cannot be solved.

Has swap changed again and I missed it?  That's entirely possible.
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