Date: Sun, 28 Jan 2007 04:13:28 +0100 From: "Hansa" <mythtv@logic-q.nl> To: "R. B. Riddick" <arne_woerner@yahoo.com>, "freebsd geom" <freebsd-geom@FreeBSD.ORG> Subject: RE: How do I gmirror slices? Message-ID: <LHEFLGAENILPPDJIHADOMEIACFAA.mythtv@logic-q.nl> In-Reply-To: <20070127230930.96837.qmail@web30305.mail.mud.yahoo.com>
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First of all. Sorry for the other messages. I had some problems sending mail to the list. > Van: R. B. Riddick [mailto:arne_woerner@yahoo.com] > > Currently ad4 contains 3 partitions: > > ad4s1 swap, / and /var > > ad4s2 /usr > > ad4s3 /home > > I wan't to mirror ad4s1 and ad4s2. I want to stripe ad4s3. Below is my > > current slice setup. > > > So u have another disk? Yes, forgot to mention. > Or do u want to mirror ad4s1 to ad4s2? That would be not so wise > (performance, > safety)... > > > Offset Size(ST) End Name PType Desc Subtype > > Flags > > > > 0 63 62 - 12 unused 0 > > 63 12578832 12578894 ad4s1 8 freebsd 165 > > 12578895 147814065 160392959 ad4s2 8 freebsd 165 > > 160392960 425706435 586099394 ad4s3 8 freebsd 165 > > 586099395 15309 586114703 - 12 unused 0 > > > > Before I continue setting up the mirror I want to make sure > I've setup my > > slices correctly. > > Reading the gmirror man page it states that the gmirror utility > uses on-disk > > metadata (stored in the provider's last sector) to store all needed > > information. > > Since I'm no expert in understanding disk structures I'm not > sure what the > > above means. > > > gmirror/gstripe use the last sector of its consumers for meta > data, and provide > a device that is one sector shorter than the smalles consumer. > > E. g.: > gmirror(name=X, consumers=(ad99s1(size=1GB), ad77(size=2GB)), > size=1GB-512B) Not sure what you mean by the above. I'm not familiar with the terms you (and gmirror manpage) use. Where do I place the consumer; what is the provider's last sector? Though I speak an read English fairly well, it is not my native language and sometimes it's hard to understand writings in it :) Considder my setup below: [----------------------- ad4 ----------------------] (disk) [--------- s1 ---------][---- s2 ----][---- s3 ----] (slices) [[--a--][--b--][--d--]*][[--- d ---]*][[--- d ---]*] (partitions) I think the metadata is stored at '*' Is it one sector (512Bytes?) smaller than size(a) + size(b) + size(d) (same for s2d and s3d). > > In my case I think I should create the folowing slice setup: > > my last partition on ad4s1 must end at 12578893 instead of 12578894. The > > next partition should begin at 12578895 and end at 160392958 > creating the > > space to store metadata. > > > The problem with an existing installation is, that it is possible > that the last > sector of ad4s1 and ad4s2 and ad4s3 is used by a file system. So > we need to > know the bsdlabel of ad4s1 and ad4s2 and ad4s3 in order to give > useful advice. Here they are: # /dev/ad4s1: 8 partitions: # size offset fstype [fsize bsize bps/cpg] a: 4192256 0 4.2BSD 0 0 0 b: 4192256 4192256 swap c: 12578832 0 unused 0 0 # "raw" part, don't edit d: 4194320 8384512 4.2BSD 0 0 0 # /dev/ad4s2: 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 147814065 0 unused 0 0 # "raw" part, don't edit d: 147814065 0 4.2BSD 2048 16384 28552 # /dev/ad4s3: 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 425706435 0 unused 0 0 # "raw" part, don't edit d: 425706435 0 4.2BSD 2048 16384 28552 > I just wonder why u want to stripe (without any safety) the home fs, which > contains most likely quite important and difficult to restore > data, while u > want to mirror (with disk failure protection) the root-fs (/), > although u can > just put a CD into ur box and restore it... R u sure, that u dont want to > mirror ur home fs, too (or graid3 (e. g. 2disks (data) +1disk > (parity)) or so)? Home is mainly used to store music and movies. I plan to tar other improtant data to the mirror. I'd like to do raid5. But since I currently lack time to install and configure a complete new system I thought this was the quickest way. Also my disks are not the same size and it would be a shame to loose the space left on larger onces :) - Hansa
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