Date: Thu, 2 Jan 2003 04:03:38 -0800 From: "Sean Hamilton" <sh@planetquake.com> To: <hackers@freebsd.org> Subject: Re: ATA RAID performance (numerous fs related questions) Message-ID: <000601c2b256$fc658b40$31dfe8d8@slugabed.org> References: <200301021006.h02A6wEe036256@spider.deepcore.dk>
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From: "Soeren Schmidt" <sos@spider.deepcore.dk> | Uhm, what kind of disks, stripesize etc are you using, without that info | noone can tell you why... Two Seagate 80GB 7200RPM drives each on their own ATA66 channel. They're not very fast, but they are quiet. Quick tests with dd show about 20 MB/s reads off them with a blocksize of 64KB. I then created a stripe with atacontrol create stripe 128 ad4 ad6 and performed the same dd on ar0, I get about 17 MB/s (on a K7 500.) The performance isn't very relevant in this case. I was just curious. Is there any reason to use span instead of stripe? I am booting off a different disk, and as I understand, if either drive craps out, there's not much hope of recovery for me anyways. Also, which newfs settings would be wise for me? I will only be storing files of exactly 10,000,000 bytes, they will be deleted and recreated often. They will be written slowly and sequentially, at around 40 KB/s (always one at a time.) They will be read as fast as possible several times thereafter, then deleted. The application I am using does not ftruncate before writing, and I am not in a position to change the code. I'm trying -m 0 -o space, though I've heard this is unwise. Can I prevent newfs from writing out superblock backups? Is async faster than softupdates? Is there any reason to use async and softupdates simultaneously, or are they mutually exclusive? (tries, but fails to think of more lingering questions) thanks, sh To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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