swap - 2 HDs
Hi list, I have a machine with: dual processor AMD 64 bits, 4 GB RAM and 2 HDs SCSI 73 GB. How can I configure the swap area ? Is It recommended to configure swap area in both HDs ?? How large ?? Aguiar ___ Yahoo! doce lar. Faça do Yahoo! sua homepage. http://br.yahoo.com/homepageset.html ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: swap - 2 HDs
On Fri, Dec 16, 2005 at 09:33:57AM -0300, Aguiar Magalhaes wrote:
I have a machine with: dual processor AMD 64 bits, 4
GB RAM and 2 HDs SCSI 73 GB.
How can I configure the swap area ?
If you haven't completed the install, make the swap during the
install when you configure the disks. If you've already finished the
install, the Handbook has a section[0] describing methods for adding
swap.
Is It recommended to configure swap area in both HDs ??
I don't see the point -- swap is where pages that don't fit in your
real memory go. It's less optimal than real memory in terms of
latency, but I don't see how two disks would make swap performance
much better.
How large ??
I'd suggest 1-4G of swap depending on whether you need to read full
dumps of the kernel/memory for debugging. If you don't, you'll
probably be fine with a lesser amount of swap, unless you'll be
running applications which will overload the memory.
[0]
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/adding-swap-space.html
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Re: swap - 2 HDs
Will Maier wrote: On Fri, Dec 16, 2005 at 09:33:57AM -0300, Aguiar Magalhaes wrote: Is It recommended to configure swap area in both HDs ?? I don't see the point -- swap is where pages that don't fit in your real memory go. It's less optimal than real memory in terms of latency, but I don't see how two disks would make swap performance much better. This is contrary to the usual advice which is to split swap across disks AFAIK. I've never done any benchmarks, but my gut feeling would be that if the disks were on separate controllers, and if the machine did swap regularly then two swap partitions would be beneficial. Even on the same controller it could easily make a difference since individual IDE/SATA disks can't actually reach the performance of the channel as a whole. Given that these are large hard disks, what's 2 or 4Gb in the grand scheme? A drop in the ocean, so I would (and do) put swap on both. Of course, if the machine actually swaps regularly then investing in more RAM would give the best performance! --Alex PS If the two disks are larger than your actual needs, then you might want to consider emergency scenarios like one of your disks dieing. If, for example, you put a spare, bootable version of FreeBSD on the 2nd disk to aid recovery then that OS will need a swap partition anyway and you might as well use it regularly. $0.02 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: swap - 2 HDs
Will Maier wrote: On Fri, Dec 16, 2005 at 09:33:57AM -0300, Aguiar Magalhaes wrote: Is It recommended to configure swap area in both HDs ?? I don't see the point -- swap is where pages that don't fit in your real memory go. It's less optimal than real memory in terms of latency, but I don't see how two disks would make swap performance much better. This is contrary to the usual advice which is to split swap across disks AFAIK. I've never done any benchmarks, but my gut feeling would be that if the disks were on separate controllers, and if the machine did swap regularly then two swap partitions would be beneficial. Even on the same controller it could easily make a difference since individual IDE/SATA disks can't actually reach the performance of the channel as a whole. From observation one can see that freebsd use the swap-partitions equally. You probarly do want to make swap-partitions on all disks, but you may later want to swapoff what is on the most busy disk if the disks are unequally busy. -- Lars Given that these are large hard disks, what's 2 or 4Gb in the grand scheme? A drop in the ocean, so I would (and do) put swap on both. Of course, if the machine actually swaps regularly then investing in more RAM would give the best performance! --Alex PS If the two disks are larger than your actual needs, then you might want to consider emergency scenarios like one of your disks dieing. If, for example, you put a spare, bootable version of FreeBSD on the 2nd disk to aid recovery then that OS will need a swap partition anyway and you might as well use it regularly. $0.02 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: swap - 2 HDs
This is contrary to the usual advice which is to split swap across disks AFAIK. I've never done any benchmarks, but my gut feeling would be that if the disks were on separate controllers, and if the machine did swap regularly then two swap partitions would be beneficial. Even on the same controller it it would be beneficial when at least two processes doing pagein/pageout. which is normal on loaded machine which needs swapping. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
