Just for the records, SCSI cards have their own processors to handle disks I/O while IDE drives are handled by the computer main processor(s). SCSI is just like "outsourcing" the drives management. So, when running processor intensive applications such as mathematical applications, the difference between SCSI and IDE tech is notorious, but this difference is not so noticeable with database processing.
When I used a 486 as my main computer, I used SCSI and divided swap into multiple small dedicated drives, so I could improve system performance dedicating the microprocessor to what it is supposed to do. Best regards, -Manuel. -----Original Message----- From: Gordon Messmer <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Date: 05 Nov 2002 09:39:59 -0800 Subject: Re: Why are IDE drives so much slower in Linux? > On Tue, 2002-11-05 at 07:25, Luis Hernandez-Garcia wrote: > > We've noticed in our lab that the machines that have IDE hard disks > run > > their write operations(ie- things that use a lot of swap space) > > Why would "write operations" use a lot of swap space? > > If you're having problems with bad performance because of swap issues, > the kernel version you're running would be useful information. You > definitely want to use the latest errata kernel for your distribution, > if you're not. > > If the problem is that you're swapping excessively, it's probably > related to the VM in your kernel more than the IDE disks. > > > slowly than when we execute the same sort of operations in WIndows > machines > > (Matlab, for example), and orders of magnitude slower than the > machines that > > have SCSI drives. The IDE machines grind almost to a halt, whereas > the SCSI > > ones fly through the operations, and the Windows+IDE machines do just > fine. > > I'd be very inclined to believe that your SCSI machines have a great > deal more RAM, and swap less. > > > I know that SCSI is inherently faster than IDE > > There tends to be a greater throughput when using multiple devices, > because SCSI can do command reordering for optimization, as well as > multiple outstanding commands to distinct devices. It's "faster" when > you have more than one device per channel. However, in the case of one > device per channel, as you will find on 3ware RAID products, for > instance, performance may be just as good as with SCSI products. > > > and the Linux/Unix have been developed with SCSI in mind. > > No they haven't. > > > But, isn't there a way to optimize the system > > so that it uses the IDE drives more efficiently? Any hints? I, and > > everyone around me would sure appreciate them. > > 1: Update your kernel > 2: Check your DMA settings: > /sbin/hdparm /dev/hda > 3: Turn on DMA in /etc/sysconfig/harddisks if it's not enabled. > > > > > -- > redhat-list mailing list > unsubscribe mailto:redhat-list-request@;redhat.com?subject=unsubscribe > https://listman.redhat.com/mailman/listinfo/redhat-list -- redhat-list mailing list unsubscribe mailto:redhat-list-request@;redhat.com?subject=unsubscribe https://listman.redhat.com/mailman/listinfo/redhat-list
