Date: Fri, 11 Aug 2000 15:35:17 -0700 From: Mike Smith <msmith@freebsd.org> To: Mike Tancsa <mike@sentex.net> Cc: hardware@FreeBSD.ORG Subject: Re: 3ware and RAID0 vs RAID 1 Message-ID: <200008112235.PAA00819@mass.osd.bsdi.com> In-Reply-To: Your message of "Fri, 11 Aug 2000 10:07:00 EDT." <4.3.2.7.0.20000811092428.00da32d0@marble.sentex.ca>
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> >Ok, thanks. It *definitely* shouldn't "just hang" at all. > > OK, some more quick testing... I was wrong about the hanging, I just did > not wait long enough. That's a relief. I take it that you didn't look at the disks? > running bonnie with 100M (the machine has 128M of RAM, both complete in > about 30seconds. Actually, 33 for the 3ware vs 30. Sounds reasonable. > (mounts are sync btw) > > -------Sequential Output-------- ---Sequential Input-- > --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- > --Seeks--- > Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > IDE 100 15511 84.5 16221 30.4 17630 33.8 13662 99.9 159587 99.9 > 17239.3 99.7 > RAID1 100 18210 97.4 18148 32.5 19653 36.0 13644 100.0 157095 100.0 > 17101.5 99.6 > > > But, when I do something over my available RAM, the differences become very > apparent. > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > IDE 500 17721 93.8 18197 33.4 8871 21.2 12800 97.5 22265 21.2 153.1 1.9 > RAID1 500 14711 81.0 16023 32.0 600 1.4 5805 44.0 6710 6.0 102.2 1.3 > > Doing a 500MB write on a regular drive on this machine takes about 3min, > 30seconds. On the RAID1, it takes 19 min ?? Can you be more specific about "a 500M write"? Are you referring to the bonnie run? I wouldn't expect it to be 5x as slow. Note that the rewrite case suggests that your test is still too small; I typically use 1 or 10GB on a 128MB machine. > Do you see similar results with your controllers and disks in RAID1 ? Bonnie results on these cards tend to suggest that they're fairly slow writers. It's 3ware also observed this, but commented that with two writers they found more bandwidth. I suspect that the write overhead may be fairly high, leading to a lot of dead time while writing (the read overhead is also an issue I guess). I haven't done a lot of timing tests, as I'm typically more concerned with functionality and reliability. -- ... every activity meets with opposition, everyone who acts has his rivals and unfortunately opponents also. But not because people want to be opponents, rather because the tasks and relationships force people to take different points of view. [Dr. Fritz Todt] To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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