Need dmraid to support fakeraid.

Asked by alteeno on 2007-03-22

Wishing that dmraid will be integrated into the Feisty Dist.

Question information

Language:
English Edit question
Status:
Answered
For:
Ubuntu dmraid Edit question
Assignee:
No assignee Edit question
Last query:
2007-04-15
Last reply:
2007-04-20
alteeno (alteeno-sina) said : #2

What I mean is that I hope the (K)ubuntu intaller will support the fakeraid. Till the 6.10, the (K)ubuntu alternate CD isn't support the fakeraid.

Personally I would not use fakeraid even if it was supported in Linux. Linux has its own software RAID implementation which is far superior than the awful cheap not-really-RAID systems that manufacturers put on motherboards.

As an example, if your motherboard goes bang, you can take those disks to another machine and use them immediately to get the data off the disk. If you use fakeraid, chances are you wont be able to do that unless you buy exactly the same make/model of motherboard/disk controller.

Chad Bernier (berniercr) said : #4

Alan, people need fake raid support because it's the only way for the same array to be read/write able by windows and linux. windows and linux software raid systems are incompatible.

Judging from the fun and games I've had with Debian Etch and dmraid, I'd say that it would be nice to have dmraid there, but keep quiet about it. I basically had to debootstrap manually since the LVM/RAID part of the install became horrendously confused. Even after fighting grub and getting everything working, when a disk died, dmraid refused to activate the degraded array (so I had to boot into another operating system to get it array back online before booting back into linux..)

So in answer to the original question, dmraid tools are in the universe repository but not on the live cd. You can however install the dmraid tools on the live cd, but it's unlikely (given they are in the universe repository) that they will be included in the Feisty CD.

Chad Bernier (berniercr) said : #7

Alan, that is a poor decision on part of the Ubuntu team. I know someone who used to love Ubuntu, and has switched to Fedora Core. I'm still using Ubuntu for now, but Fedora Core seems to get features first, like dmraid support on the LiveDVD.

if i can't get my raid 5 working in ubuntu soon, I might try FC on that computer. If i like the results, it may go on my other computers.

Chad, I fail to see how including a (current) badly broken technology solution on the live CD is a good idea. Maybe if it gets more mature it might be a good idea, but right now, I don't see how any distro can claim that dmraid is production quality.

If you would like to see dmraid on the live CD then there is a process in place to petition for packages to be moved from the universe repository to main, and thus possibly get included on the CD.

MightyE (mightye) said : #9

Alan, I appreciate your dialog on the matter.

I would suggest that many computer "enthusiasts" have purchased hardware which was advertised as Raid# when they purchased it, and as far as they will be able to tell, either Ubuntu obliterated their existing OS if they attempt to install w/o dmraid, or at best, simply fails to support their hardware. Respectfully I would suggest that this ignores users with anything other than an especially above average understanding of hardware.

A new demographic of user is migrating to Linux in general, and especially toward Ubuntu; average users who don't actually know much about hardware but enjoy tinkering around with things. If you're looking to get into the Linux scene, lack of support on something which is becoming the defacto standard for all high end home systems can leave a bad taste in the mouth at best, or result in a counter-convert at worst.

I would recommend at a minimum, include dmraid on the live CD, but also include a warning message with it to the effect of, "Please note, your hard disk configuration relies on a package entitled dmraid, which supports many false RAID controllers (commonly associated especially with SATA RAID controllers). Although these products are advertised as being RAID controllers, they are in fact only hardware-assisted RAID. Although early support for such configurations exists in Ubuntu, you should note that this is not considered to be final or production ready. If you choose to proceed, please be very sure that you have backed up any important data on existing partitions. Please follow this link for further information and some helpful additional instructions: http://link.to/wiki/dmraid"

Otherwise there is no way that a normal human could be expected to understand they should be installing some random package called dmraid, and they won't understand that it's actually cheap hardware standing in their way, all they'll see is Windows works fine, Linux doesn't. Ubuntu should be focusing especially on satisfying such cusp users.

alteeno (alteeno-sina) said : #10

Firse I use redhat and fedora the following. When a friend tell me there is a good linux dist called ubuntu, I had a test. The ubuntu support my epson rx430 and the Fedora doesn't, So I change my OS to Kubuntu, And I love it. Now I have four disk to use raid10, The Fedora Install CD support the fakeraid and the Kubuntu Install CD doesn't. Perhaps It's time for me to reture the Fedora's arms if the (K)ubuntu does still NOT support the fakeraid.

Chad Bernier (berniercr) said : #11

windows can boot off of fake raid 5 array no problem. all you have to do is make sure the driver disk is in the pc, or the drivers were integrated onto the CD. Linux still can not do this, especially without a lot of tinkering.

Windows is extremley annoying. linux is extermelty annoying. OSX requires special hardware, and I'm sure is exteremly annoying. you can't win in the OS game.

Linux's worst problems are due to the fact that many companies don't support them. lack of drivers, lack of propietary software, etc. the main reason they don't support it is due to the low market share. People won't switch to linux though until things are better. the best you can hope for is dual booting situations. However, if important things like raid support don't exist, why even bother dual booting?

think of this situation. A build a new computer with 6 SATA ports in a case that holds 6 HDD. i put them all in raid5. how to boot linux? you'd need a 7th hard drive. you'd need to use the IDE ports, or buy a pci sata card. there's no room in the case for it. it's a single hard drive, so it's slow, and failure means loss of all data. you just made people spend extra money to get linux on thier computer for a worse experience. way to go! I'd much rather take my chances with unfinished software. So far, dmraid hasn't given me a single problem once set up.

I don't need official support right now, but how about unofficial support? you don't have to worry about stuff like this with gentoo. If it's possilbe you can do it with gentoo and someone wrote instructions on how to do it. but I'm sick of the gentoo install process so i tried ubuntu. but i don't think even gentoo can support booting off fake raid5 yet, I've done raid0.

4 port real raid adapters aren't too pricy, but 8 port ones are. since anything less than 5 HDD in a raid5 array is incredibly wasteful (20% space waste is the most i'm willing to do), I'd need a 8 port unit.

i've been planing a great computer for a long time but keep putting it off due to the fact that I don't actually need it. someday it will be built. it will have raid5.

options.

Software raid. this prevents the direct installation of windows without extra HDD. Windows can't boot off of windows software raid, as far as i know. So you have the crappy OS windows running on a single, relatively slow hard drive, with it's poor memory management. It can't access any of the data on the array. or did somebody write a windows driver to do that? alternative is not to have windows. as much as i'd like that, it has many problems of its own.

hardware raid. very expensive. if I'm going to have the ports, might as well use them all. so now i need a 6 disk raid5 array, and a 2 disk raid0 array. with all that investment in a 8 port hardware raid controller, you bet I'm going to use raid0 to install windows and linux on. back up the data to the extermely large raid5 array. So now you got me buying 8 hard drives, plus the case, cables, power supply, etc to support that. even if i end up going with a 5-6 disk plan, it's still quite expensive.

fake raid. Cheap, already included on the motherboard, paid feature, should use it. linux won't boot from it, and even getting it to read the array is difficult and risky. this would certainly require the 6 +2 hard drive plan, unless linux can boot directly from raid5. or a 5 +1 plan, which puts your OS on a single drive.

Software raid is out the window if you want windows. hardware raid is expensive. fake raid could be ok if better software is written for it.

an alternative option is putting the raid5 array in a different box, and just using fake raid0 for windows and linux. this allows the main computer to be smaller and whatnot. however this is quite expensive. you either need an expensive raid/NAS server (quite expensive over 4 disks), or a whole other desktop computer, presumably running linux exclusively, and acting as a raid/nas. it's need a large case and a PCI SATA card though. I don't trust my current desktop to this task, as it isn't stable. It has a faulty graphics card, and I haven't found good cpu settings to keep it stable. maybe that can be fixed up to serve as that option. although I'd still consider that a waste of its capabilities.

I still don't know what i want to do. I do know though, that i want fake raid5 support fixed up and hopefully bootable someday soon. the more expensive the planned computer, the longer i have to wait to justify it. a $250 raid controller doesn't make that easier.

Tormod Volden (tormodvolden) said : #12

For those interested, we are working on a specification on dmraid support in Ubuntu: https://wiki.ubuntu.com/FakeRaidSpec

Chad Bernier (berniercr) said : #13

that'd be a great step for Ubuntu, but isn't enough for raid5. raid 0 and 1 are the most common though. I realize that raid5 support won't be added anytime soon, but I'd hope they could at least provide a manual, unofficial solution for it.

Can you help with this problem?

Provide an answer of your own, or ask alteeno for more information if necessary.

To post a message you must log in.