Date: Tue, 14 Apr 1998 13:59:15 -0700 From: brian@litzinger.com To: bh@epigram.com, freebsd-questions@FreeBSD.ORG Subject: Re: RAID performance/benchmarking Message-ID: <19980414135915.A12460@top.worldcontrol.com> In-Reply-To: <3533BDAF.A8588F53@epigram.com>; from Brandon Huey on Tue, Apr 14, 1998 at 12:49:03PM -0700 References: <3533BDAF.A8588F53@epigram.com>
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On %M 0, Brandon Huey <brandon@epigram.com> wrote: > Dell PowerEdge 4200/300, 96MB RAM, 3 9GB Seagate Barracuda SCA drives > DPT PM3334UW w/64MB cache > > FreeBSD 2.2.6 > DPT kernel options: DPTOPT > DPT_MEASURE_PERFORMANCE > DPT_FREELIST_IS_STACK > > using IOZONE and Bonnie, i create a 128MB file for read/write > benchmarking. > > i am aware of the performance implications of RAID-5, but I am getting > about 2MByte/sec max write transfer rate compared with 19MByte/sec on > reads. In RAID 5 to write a sector requires the following: (through not necessarily in the order specified) read the parity sector (usually on a different drive than the target sector) read the target sector write the target sector write the parity sector while a read only requires a read of the target sector. So generally writing takes quite a hit. -- Brian Litzinger <brian@litzinger.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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