Date: Sun, 27 May 2001 11:45:20 -0500 From: Dan Nelson <dnelson@emsphone.com> To: Felix Hernandez <felix_hdez@yahoo.com> Cc: Bill Moran <wmoran@iowna.com>, freebsd-questions@FreeBSD.ORG, Ian Dowse <iedowse@maths.tcd.ie> Subject: Re: Slower tape drive when compression off Message-ID: <20010527114520.A5559@dan.emsphone.com> In-Reply-To: <20010527160722.3092.qmail@web9501.mail.yahoo.com> References: <20010527160722.3092.qmail@web9501.mail.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In the last episode (May 27), Felix Hernandez said: > Yes!!! Right on the nail! It was a buffer size problem. > > root@oberon $$$ mt comp off > root@oberon $$$ dd if=junk of=/dev/rsa0 bs=10k > 51200000 bytes transferred in 22.686704 secs (2256829 bytes/sec) > root@oberon $$$ dd if=junk of=/dev/rsa0 bs=64k > 51200000 bytes transferred in 9.491773 secs (5394145 bytes/sec) > root@oberon $$$ dd if=junk of=/dev/rsa0 bs=256k > 51200000 bytes transferred in 9.497948 secs (5390638 bytes/sec) BTW, the last two results are the same because FreeBSD currently has a 64K limit on SCSI I/O size. Your 256K write was internally split into four 64k ones. -- Dan Nelson dnelson@emsphone.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010527114520.A5559>