PCI-e SSD recommendation for a F22 machine

[Ian Malone]

On 4 September 2015 at 13:50, Ranjan Maitra
<maitra.mbox.ignored at inbox.com> wrote:
> Hi,
>
> On Fri, 4 Sep 2015 10:33:16 +0100 Ian Malone <ibmalone at gmail.com> wrote:
>
>> On 2 September 2015 at 21:45, Ranjan Maitra
>> <maitra.mbox.ignored at inbox.com> wrote:
>> > Hi,
>> >
>> > I was wondering if it is possible to use a PCI-e SSD for the root and swap partitions of a workstation running F22. I am thinking of installing F22 and my swap here -- the machine has 64GB memory. So I am considering getting a 128 GB PCI-e SSD, and leaving 96 GB for swap and 32 GB for /. /home will be on a different SATA HDD.
>> >
>> > Do you have any suggestions and recommendations for a 128 GB PCI-e SSD?
>> >
>>
>> Well, since you've had no more useful answers than I can give, 32GB is
>> just about enough for /. (I've squeezed home and / into that on my
>> laptop, but need to keep an eye on space). It should work provided the
>> motherboard supports it and there are modules in fedora for it
>> https://www.reddit.com/r/linux/comments/3goigc/anyone_here_running_fedora_22_with_an_nvme_boot/
>
> Thanks. Given Fedora mailing list's sudden general lack of activity from around the same time I posted, I was wondering if something had happened to the ML server.
>
> Thank you for the pointer to that webpage.
>
> There are PCI-e SSD slots on the machine, so I will take a look at the motherboard.
>
> Funny, I was looking at a 128 GB Samsung PCI-e SSD referred to in the article -- gLad to know that it works.
>
> http://www.newegg.com/Product/Product.aspx?Item=N82E16820147431&cm_re=pci_ssd-_-20-147-431-_-Product
>
>> Out of curiosity, what are you doing that needs that much memory? I
>> was going to say with 64GB you probably don't need swap until I saw
>> how much you were planning to allocate...
>
> I do a lot of computing with my computers. Some of the alternative methods that I may replace requires a lot of memory. I belong to the old school where swap mattered a great deal, and so it was recommended to put 2x memory in there. But I am not sure if that is needed to be 2x as much anymore, This is the first time I will go down to 1.5x, thought 1x may well be adequate.
>

I can think of some things that would run into that kind of memory,
but not many for normal desktop or office use. (My own area is medical
imaging where what we're doing is often 1-2GB per core, though for
some things like statistical analysis you need RAM to load all the
data into memory, then depending on sample size you could get into 10s
GB). Databases and other high end stuff like video editing also eat
RAM, but I think the 2x recommendation is probably outdated for most
cases now. We typically run machines with only a quarter the swap that
they have in RAM, because running into swap on disc is a serious
slowdown anyway, but don't eliminate it altogether as it provides a
softer landing when you run out of RAM, a system running out of memory
when swapping seems to have time to auto kill processes, while one
with no swap more often just sticks hard.

The other place lots of RAM helps is disc caching, which is of course
not helped by swap and less of a benefit if using SSD.

-- 
imalone
http://ibmalone.blogspot.co.uk