Chris, LVM is developed by Sistina Software (http://www.sistina.com/products_lvm.htm). They also have a current version of LVM-HOWTO available on their site, which seems to be more recent than the one on LDP. LVM, perhaps unlike MD, is a work in progress, current stable version, afaik, is 1.02, and there are frequent updates, both to the kernel code and the userspace tools. On the other hand, version 2 is also under development currently. In my opinion, you should use LVM if a) you will frequently need to resize your array and b) striping or the redundancy offered by raid-5 is not a high priority to you. LVM can do striping for a logical volume, but then you can't expand that LV, at least not with current implementations. On the other hand, it doesn't offer the redundancy of either raid-1 or raid-5. MD offers stability, I think it's also more widely implemented, and it offers the safest and fastest performance your array could give, under raid-5. When it comes to resizing, I tried raidreconf just last week, and Jakob, the author of this nice tool helped me a lot through the process. Even though it worked rather well (under the circumstances), my opinion is that raidreconf is ok and pretty useful if you will only have to do a resize or array conversion (e.g. raid-0 -> raid-5, or chunk-size reconfiguration) only a few times in the array's life. As disk capacity is constantly growing, and you create bigger and bigger arrays (500gb, 1tb or more), resizing/converting such an array with raidreconf will take a substantial amount of time (days). So my suggestion is, if you plan to resize your array frequently, or otherwise experiment with it (chunk-size, raid-level), if you can't backup 500+ gb of data every time to disks or other media (that also takes a long time) and especially if you don't care so much about the redundancy/performance offered by raid-5, i.e. you can live with some lost files from bad sectors you won't manage to recover if a disk goes berserk; in that case you should use LVM. You could also use a MD in LVM, but the only use I see in that is to create dynamic virtual partitions over it, while maintaining a level of redundancy at a lower level with raid, should something fail. Adding an MD in a logical volume, together with other devices, is rather a rough solution in order to expand your array, and I'm not so sure if an existing filesystem on the MD would survive after the MD was added to the LV, so that you could resize it to use all of the available capacity in the volume. Another similar, yet safer fix is what was proposed to me last week: make a new MD, consisting of the old one plus any new devices, and use linear as the raid-level of the new array. This way, the underlying fs on the old MD is preserved for you to resize and reuse. Good luck, Cajoline Leblanc > -----Original Message----- > From: linux-raid-owner@vger.kernel.org [mailto:linux-raid- > owner@vger.kernel.org] On Behalf Of Alvin Oga > Sent: Friday, February 15, 2002 8:20 AM > To: Gregory Leblanc > Cc: Linux RAID > Subject: Re: Raid-5, LVM, Reiser FS > > > hi ya > > donno if these lvm stuff relates to what you're looking for > > http://www.1U-Raid5.net/HowTo/LVM.txt > > > have fun raiding > alvin > http://www.1U-Raid5.net ... > http://www.Linux-1U.net ... > > > On 14 Feb 2002, Gregory Leblanc wrote: > > > On Thu, 2002-02-14 at 15:20, Chris Hirsch wrote: > > > Yeah! I'm finally going to do it! I got the start of my hardware and > I'm > > > going to do a Raid-5 configuration...I was trying to find an updated > > > RAID HOWTO but the newest I could find is here > > > http://unthought.net/Software-RAID.HOWTO/Software-RAID.HOWTO.html > > > > > > Is that the newest available... > > > > I believe that Jakob is very good about making sure that the LDP has the > > latest version available. http://www.linuxdoc.org, or your local > > mirror. > > > > > Are there any HOWTOs that anybody knows about on how to do a RAID-5 > with > > > LVM and a Reiser-FS filesystem? Are there are reasons not to do this? > If > > > > I don't know of any RAID HOWTOs that also cover LVM. If you're using > > the 2.4.x kernels, then I don't know of any reason not to use reiser and > > LVM. > > > > > I can dynamically resize (hopefully using the raidreconf with no > > > problems) the array does LVM get me anything? > > > > No idea, I haven't looked at LVM at all. > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
