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On Tue, 2005-04-12 at 09:26 +0300, Micha Silver wrote: > On the CentOS mailing list, a poster suggested spliting swap space into > two separate partitions on two drives. Next someone else commented that > such a scheme would cause a crash if one of the disks with part of the > swap space died. A third poster answered that it would, and that swap > space should be mirrored (!). Does this sound correct? I thought that > splitting swap space across two disks was actually recommended. > > Thanks, > Micha The problem with swap is the "bandwidth" (i.e. the amount of data you get to/from the swap). Therefore, the wider your "channel" to the swap space is, the faster it would be. As of today, the bottleneck of swap space is not the bus between the North/South bridge of the motherboard to the hard drives, but the speed of the hard drives. Therefore, if your swap space spans more than one device, you got more bandwidth to it, and your system runs faster if it uses swap. If you take part of the RAM out (and swap space _is_ part of the RAM for that matter), the machine would die, most probably... The system runs from that memory :) Mirroring the swap space (as in RAID-1), would increase your _reading_ performance, but not writing (slight performance increase, I guess). Want really good performance AND machine that doesn't hang if one of the disks die? Usually more RAM would be less expensive (methinks), but if you still want the swap, you can use RAID-10 for the swap. That way, your swap spans two (or more) disks, and is also redundant. But it's damn expensive :) Shimi --=-e2KNw2l4i15uQBuyXGM5 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 TRANSITIONAL//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=UTF-8"> <META NAME="GENERATOR" CONTENT="GtkHTML/3.2.5"> </HEAD> <BODY> On Tue, 2005-04-12 at 09:26 +0300, Micha Silver wrote: <BLOCKQUOTE TYPE=CITE> <PRE> <FONT COLOR="#000000">On the CentOS mailing list, a poster suggested spliting swap space into </FONT> <FONT COLOR="#000000">two separate partitions on two drives. Next someone else commented that </FONT> <FONT COLOR="#000000">such a scheme would cause a crash if one of the disks with part of the </FONT> <FONT COLOR="#000000">swap space died. A third poster answered that it would, and that swap </FONT> <FONT COLOR="#000000">space should be mirrored (!). Does this sound correct? I thought that </FONT> <FONT COLOR="#000000">splitting swap space across two disks was actually recommended.</FONT> <FONT COLOR="#000000">Thanks,</FONT> <FONT COLOR="#000000">Micha</FONT> </PRE> </BLOCKQUOTE> <BR> The problem with swap is the "bandwidth" (i.e. the amount of data you get to/from the swap). Therefore, the wider your "channel" to the swap space is, the faster it would be. As of today, the bottleneck of swap space is not the bus between the North/South bridge of the motherboard to the hard drives, but the speed of the hard drives. Therefore, if your swap space spans more than one device, you got more bandwidth to it, and your system runs faster if it uses swap.<BR> <BR> If you take part of the RAM out (and swap space _is_ part of the RAM for that matter), the machine would die, most probably... The system runs from that memory :)<BR> <BR> Mirroring the swap space (as in RAID-1), would increase your _reading_ performance, but not writing (slight performance increase, I guess). Want really good performance AND machine that doesn't hang if one of the disks die? Usually more RAM would be less expensive (methinks), but if you still want the swap, you can use RAID-10 for the swap. That way, your swap spans two (or more) disks, and is also redundant. But it's damn expensive :)<BR> <BR> Shimi </BODY> </HTML> --=-e2KNw2l4i15uQBuyXGM5-- ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
