A question of where to put swap
I am in the business of re-arranging my disk layouts to reflect the realities if life :) My FreeBSD system currently runs on a SCSI-3 Disk, but I have two modern, fast IDE disks that will be gaining a considerable amount of free space in the re-arrangements. I tend to run during the course of the day several extremely memory loving programs which cause paging/swapping to occur. I would like opinions on whether I would notice an improvement if I moved the swap area (which lives on the SCSI disk with the rest of the system) to the front of one of the IDE disks. I intend to make a new slice on the IDE disk anyway. I cannot afford any more memory (my mobo will not take it anyway). I ask this more out of curiosity than because it is a particular problem to me at the moment .. but future plans may change the criticality of such decisions. (I am not sure there is such a word as criticality...). Thanks for any input. -- Regards Cliff Sarginson The Netherlands [ This mail has been checked as virus-free ] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-questions in the body of the message
Re: A question of where to put swap
On Fri, 2002-11-22 at 09:44, Cliff Sarginson wrote: I am in the business of re-arranging my disk layouts to reflect the realities if life :) My FreeBSD system currently runs on a SCSI-3 Disk, but I have two modern, fast IDE disks that will be gaining a considerable amount of free space in the re-arrangements. I tend to run during the course of the day several extremely memory loving programs which cause paging/swapping to occur. I would like opinions on whether I would notice an improvement if I moved the swap area (which lives on the SCSI disk with the rest of the system) to the front of one of the IDE disks. I intend to make a new slice on the IDE disk anyway. I cannot afford any more memory (my mobo will not take it anyway). I ask this more out of curiosity than because it is a particular problem to me at the moment .. but future plans may change the criticality of such decisions. (I am not sure there is such a word as criticality...). Thanks for any input. I believe you are supposed to put a swap partition on every physical disk, up to 4, for optimum swap usage, allowing enough space for future memory expansions (which doesn't seem relevant here). I'm not sure how mcuh swap is good, but I think it's at least twice physical. As far as where to put it, I have seen various recommendations on putting swap on the outside of the disc (presumably to do with angular velocity) which I guess is the front. The first partition is where I put the swap on my Mac, but I can't say if it made any difference, since Apple seems to think everybody wants one big disk and makes it really difficult to use partitions effectively. As far as FreeBSD goes, it at least lets you do what you want if you are savvy enough to know what you are doing, and I can't see that it would hurt. Perhaps you could do some benchmarking? -- The information contained in this email is confidential. If you are not the intended recipient, you may not disclose or use the information in this email in any way. Dark Blue Sea does not guarantee the integrity of any emails or attached files. The views or opinions expressed are the author's own and may not reflect the views or opinions of Dark Blue Sea. Dark Blue Sea does not warrant that any attachments are free from viruses or other defects. You assume all liability for any loss, damage or other consequences which may arise from opening or using the attachments. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-questions in the body of the message
Re: A question of where to put swap
On Fri, Nov 22, 2002 at 12:44:54AM +0100, Cliff Sarginson wrote: I am in the business of re-arranging my disk layouts to reflect the realities if life :) My FreeBSD system currently runs on a SCSI-3 Disk, but I have two modern, fast IDE disks that will be gaining a considerable amount of free space in the re-arrangements. I tend to run during the course of the day several extremely memory loving programs which cause paging/swapping to occur. I would like opinions on whether I would notice an improvement if I moved the swap area (which lives on the SCSI disk with the rest of the system) to the front of one of the IDE disks. I intend to make a new slice on the IDE disk anyway. A good thing to do is to put a swap partition on each disk[*]. That permits the system to maximize IO throughput while paging. You can divide up your total required swap space between the three disks however you want, but remember that to be able to get a system crash dump, you need at least one of your swap areas to be slightly larger than the amount of RAM in your machine. Having approximately equally sized swap areas gets the absolute maximum performance out of the machine --- see The Handbook, Section 6.2.1.2 http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-initial.html Cheers, Matthew [*] so long as the IDE drives are on different channels --- you won't gain anything by having swap areas (or any areas of high disk IO for that matter) on both Master and Slave on the same channel. -- Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-questions in the body of the message
