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Centos 32 vs 64 - Is 64bit best for high ram?
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Centos 32 vs 64 - Is 64bit best for high ram?

Howdy

I've been moving some hosted sites around. I've mainly been using a OpenVZ 2gb Ram with OS Centos 6 32bit. My average is 215mb ram being used.

Today I moved some sites over to a OpenVZ 12gb with OS Centos 6 64bit. Average ram is 580mb.

After doing some reading I have found that it is normal for 64bit to sometimes use significantly more ram. The reason I went with 64, is because I also read it's best to use it when your total ram available is greater than 3gb. But there seems to be conflicting information on this.

Long Story Short. I'm curious what you guys think is best for long term when the ram is exceeding 3-4gb. 32 vs 64 bit?

Thanks for reading!
Looking forward to any comments, advice and flames :)

Patrick

Comments

  • There's more to it then that. Is it the exact same setup besides 64bit? Is it even the same OpenVZ setup? VSwap? Burst etc?

  • If you have more than 3.5GB RAM for your VPS, use a x64 version. Even though 32-bit templates are still able to address all the RAM past 4GB, the per-process limitation is still present. Using a x64 template will avoid that. Also, a x86 program might freak out if there's more than 4GB RAM and it has no idea what to do about it.

  • 64-bit versions, other conditions equal, are generally faster. There are many a factor to take into account, but if RAM is much enough, I prefer 64-bit.

  • agentmishraagentmishra Member, Host Rep

    till you do not reach the limits, enjoy using the 32bit version

  • Thanks for the replies! I feel confident now that 64bit was the right decision.

    Thanks again :)

  • BrianHarrisonBrianHarrison Member, Patron Provider

    If you're using over 4GB RAM, in most cases it's advisable to switch to 64bit. Nice simple explanation: http://lifehacker.com/5431284/the-lifehacker-guide-to-64+bit-vs-32+bit-operating-systems

  • i am use centos 5 64bit in to vps 1GB ram and no issue ram usage
    i see system still running normal

  • smansman Member
    edited October 2013

    @Master_Bo said:
    64-bit versions, other conditions equal, are generally faster.

    Really? Got any benchmarks to back that up? Not just for some specialized applications but general use.

    Only factor imho is if you have more then about 3.5Gig RAM which is usually the case now a days.

  • @sman said:
    Really? Got any benchmarks to back that up?

    Of course. Long experience working with both 32-bit and 64-bit versions, plenty of time to compare. As I said, when RAM is not an issue, I use 64-bit versions.

  • smansman Member
    edited October 2013

    @Master_Bo said:

    I have not found any significant difference in performance between 32 and 64. There may be some highly specialized applications where 64bit has a mathematical advantage but nothing for general purpose use in my experience.

    64bit also uses more memory for accomplishing the same things. Not much of a problem now a days when 8, 16, and even 32GB of memory is common. A bit of a factor on VPS which is why I suggest 32bit for VPS. If someone really want's a 64bit VPS I have no problem with that either. Even on a 512MB box it's not much more memory for general purpose things.

  • MrRadicMrRadic Patron Provider, Veteran

    You won't see much of a performance difference, the main difference is the obvious support for more memory and generally 64 bit applications consume more memory.

  • @MrRadic said:
    You won't see much of a performance difference, the main difference is the obvious support for more memory and generally 64 bit applications consume more memory.

    True. 64-bit versions consume more RAM and more disk space.

    However, there are applications (mostly those related to calculation) which can benefit from 64-bit mode (exhibit noticeable performance gain). Those include database engines, multimedia processing applications, CGI etc. POVRay can be a good example.

    For low-memory servers 64-bit can result in significant performance degradation. So, nothing is more valuable than personal experience - when in doubt, run benchmarks and select optimal architecture.

  • 32 bit only supports upto 3GB RAM 64bit 3GB RAM+

  • You can also run a 32bit PAE enabled kernel which runs multiple 4Gig memory pieces. I know it's available for OpenVZ but not sure about general distributions like CentOS.
    http://en.wikipedia.org/wiki/Physical_Address_Extension#Linux

    I've run it and it works as advertised. I think there is a bit of a performance hit so 64bit is preferred.

  • emgemg Veteran

    If you have sufficient RAM, then another reason to consider 64-bit is the long term view. Future trends point towards 64-bit. As more and more people adopt 64-bit operating systems, they will get more active use, testing, and attention than their slowly dwindling 32-bit counterparts.

  • I would say that if you have more than 2 gb of ram, definitely go with 64bit. So in your case if you already have 3-4gb of ram 64bit is the best option, and in the long run you are eventually going to have to upgrade to a 64bit server, mine as well do it now.

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