Date: Thu, 14 May 2009 15:11:49 +0300 From: =?ISO-8859-1?Q?T=F6r=F6k_Edwin?= <edwintorok@gmail.com> To: freebsd-geom@freebsd.org Subject: Re: freebsd-geom Digest, Vol 263, Issue 2 Message-ID: <4A0C0A85.50001@gmail.com> In-Reply-To: <20090514120030.7F37510656DC@hub.freebsd.org> References: <20090514120030.7F37510656DC@hub.freebsd.org>
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On 2009-05-14 15:00, freebsd-geom-request@freebsd.org wrote: > Send freebsd-geom mailing list submissions to > freebsd-geom@freebsd.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.freebsd.org/mailman/listinfo/freebsd-geom > or, via email, send a message with subject or body 'help' to > freebsd-geom-request@freebsd.org > > You can reach the person managing the list at > freebsd-geom-owner@freebsd.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of freebsd-geom digest..." > > > Today's Topics: > > 1. Re: compatibility with Linux software RAID? (Ivan Voras) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 13 May 2009 14:56:37 +0200 > From: Ivan Voras <ivoras@freebsd.org> > Subject: Re: compatibility with Linux software RAID? > To: freebsd-geom@freebsd.org > Message-ID: <gueg25$vbg$1@ger.gmane.org> > Content-Type: text/plain; charset="utf-8" > > Török Edwin wrote: > >> Hi, >> >> Apologies if this has been answered before, but is there a way to access >> (even if just read-only) RAID arrays created by Linux software raid >> tools (mdadm)? >> >> I want to test the new superpages support in FreeBSD 7.2, and do some >> performance comparisons with Linux, problem is all my data is on a >> RAID10 array. >> > > RAID is not the only problem you have - how will you access the data? > FreeBSD's ext2 file system driver isn't nearly as good for any kind of > realistic performance testing - you'd probably need to test Linux with > extX and FreeBSD with UFS2. > I can test FreeBSD booted with superpages enabled vs FreeBSD booted without superpages enabled. You're right that comparing FreeBSD w/ Linux FS vs. Linux w/ Linux FS is not fair. I could copy the data to a temporary ramfs storage, and test from there to eliminate filesystem differences. (not taking the time needed to copy the data into account). > >> Also if gmirror does support the above, is there a way to tell it to >> treat the disks as readonly? >> > > Both gmirror and gstripe can work in a sort of "on-the-fly" mode, > without actually committing any configuration to the drives (see the > "create" command in both). In theory, you could use gmirror and gstripe > with exactly the same parameters as you did in Linux to reconstitute > your data. You'll also probably need gnop to align data before using > gmirror and gstripe. Of course, only do this if you're completely sure > what you're doing and know how RAID10 is physically implemented. > Thanks, I'll do some experiments in a VM first, and if it all works I'll move on to testing with the real drives. Best regards, --Edwin
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