Date: Wed, 08 Jun 2005 12:33:06 -0400 From: Paul Mather <paul@gromit.dlib.vt.edu> To: freebsd-current@freebsd.org Cc: "Raphael H. Becker" <rabe@p-i-n.com> Subject: Re: Accessing SCSI-Devices >2TB Message-ID: <1118248386.7479.10.camel@zappa.Chelsea-Ct.Org> In-Reply-To: <20050608152459.BF24E16A45C@hub.freebsd.org> References: <20050608152459.BF24E16A45C@hub.freebsd.org>
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On Wed, 8 Jun 2005 17:24:35 +0200, "Raphael H. Becker" <rabe@p-i-n.com> wrote: > On Wed, Jun 08, 2005 at 11:01:52PM +0800, Xin LI wrote: > > > > Well, I'm pretty trained in configuring that RAID now so if anyone > knows > > > a solution, how to get rid of the 2TB-Limit for one drive > (/dev/da1), > > > maybe using larger blocks of about 1k or 2k, I just need to > configure > > > that RAID as a single large logical drive. > > > > > > Just tell me about the blocksizes (see other mail). > > > > Err... You don't need to play with the drivers/CAM stuff, why not > try the > > natively supported gpt(8), which works great. > > > > - Map the RAID device to a single SCSI device > > - Do a dd if=/dev/zero of=/dev/da0 bs=16384 count=16 to wipe > the MBR > > Well, without a /dev/daX there's nothing to use gpt with. The kernel > itself cannot access the RAID as a whole. See my other mail for the > kernel messages. > > My workaround was to partition the RAID's logical disc into two > partitions > internally and re-concat the resulting da1 and da2 into ccd0. > But this might also be a bad idea therefore ccd0 is will do stripes > and > the RAID will have to seek the physikal drives a lot for each (linear) > access. > > Two solutions: > a) FreeBSD can access the RAID using LBA64 and get a da1 having > ~2.5TB > > b) I have to split the RAID on physical drive layer, having 6 disks > for > each logical drive (losing hot-spare (cannot divide 11 discs into 2 > equal logical drives) and need a additional parity, one for each > logical > drive) and mapping those to two different LUNs or IDs and using the > resulting > 1.3TB-drives da1 and da2 with ccd(4) and then ... > > > - Do a `gpt create /dev/da0' to create your GPT partition > table > > - Do a `gpt add /dev/da0' to create a GPT partition over it > > - You will now see something like /dev/da0p1, which can be > used for > > subsequent disklabel(8), or just newfs -U /dev/da0p1 > > ... will try this, if the device is clear. Thank you for the hint > about gpt. You might want to check the "Large data storage in FreeBSD" project page (http://www.freebsd.org/projects/bigdisk/) for an audit of other issues relating to large filesystems in FreeBSD. I don't know how up to date the page is (it reports being last modified mid-February, 2005), but currently it still lists various issues with some userland tools and subsystems not being 64-bit clean. Also, have you considered using geom_stripe for concatenation? It postdates ccd. See the gstripe(8) man page for details. Cheers, Paul. -- e-mail: paul@gromit.dlib.vt.edu "Without music to decorate it, time is just a bunch of boring production deadlines or dates by which bills must be paid." --- Frank Vincent Zappa
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