Date: Wed, 22 Jan 2003 21:28:16 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Noah Garrett Wallach <sleek@enabled.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: iostat - define Kilobits per transfer Message-ID: <20030123032816.GA1799@dan.emsphone.com> In-Reply-To: <20030122191542.J76039@typhoon.enabled.com> References: <20030122191542.J76039@typhoon.enabled.com>
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In the last episode (Jan 22), Noah Garrett Wallach said: > can somebody give me a better understanding of what the iostat output > is decribing in the KB/t column. It might be really simple but > figured I';d ask, if in fact further clarification can be given. > > typhoon% iostat 1 > tty da0 da1 acd0 > tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in > 0 21 0.00 0 0.00 0.00 0 0.00 0.00 0 0.00 1 0 1 0 > > do drive specifications generally contain KB/t information or statistics? When there is disk activity, yes. Try running a couple du's or extract a couple ports, then run iostat in another window. > I currently have an IDE drive that has the capacity to do 128KB/t and > a SCSI drive 64KB/t. Are these stats in fact showing me that there > is a limitation with the SCSI drive? Are my file transfering > capaibilities less with the SCSI drive? I suppose what do I need to > look for in the spcifications when choosing new drives so this does > not happen again? FreeBSD's SCSI layer has a cap of 64k per transaction (apparently because ancient ISA adapters could not do more than 64k), and the ATA layer has a cap of 128k. You won't see a difference using regular disks. A 20MB/sec transfer rate comes out to ~300 64K transactions/sec, which most systems should be able to handle with no problems. -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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