RE: raid-2.2.17-A0 cleanup for LVM
> -Original Message- > From: Carlos Carvalho [mailto:[EMAIL PROTECTED]] > Sent: Monday, August 07, 2000 10:57 AM > To: Andrea Arcangeli > Cc: [EMAIL PROTECTED] > Subject: Re: raid-2.2.17-A0 cleanup for LVM > > >In 2.2.x that's not possible but for _very_ silly reasons. > > So can't this be fixed? I wouldn't expect it to be fixed. 2.4 is well on it's way, and seems to have quite a few "silly" things fixed. > >On 2.4.x we now have a modular and recursive make_request > callback, that > >will allow us to handle all the volume management layering > correctly (so > >if raid5 on top of raid0 isn't working right now in 2.4.x send a bug > >report ;). > > Yes, but it's useless because of the abysmal (absence of) speed. And > all the VM problems... The machine I need raid50 on is a central > server, if it stops everything else goes down. In fact I'm not using > 2.4 on it precisely because of the VM/raid problems!! :-( :-( > > If I can't do raid50 on our server I'll have to resort to raid10, > losing 50% of our so expensive disks... No, DASD (disks) are cheap, compared with other things, like upgrading the processor(s) on your oracle or DB2 server. If you're dealing with SCSI (which you must be, for that many drives), and using RAID 5, speed can't be that paramount. Just put another drive on each bus. I know, nobody likes to spend money on disks, but they're cheaper than losing data. Greg
Re: raid-2.2.17-A0 cleanup for LVM
On Mon, 7 Aug 2000, Carlos Carvalho wrote: >So can't this be fixed? Everything can be fixed, the fact is that I'm not sure if it worth, we'd better spend efforts in making 2.4.x more stable than overbackporting new stuff to 2.2.x... The fix precisely to allow raid5 on raid0 could be pretty localized if done in the wrong way though (with wrong way I mean not in the 2.4.x way). Andrea
Re: raid-2.2.17-A0 cleanup for LVM
Andrea Arcangeli ([EMAIL PROTECTED]) wrote on 7 August 2000 16:50: >On Sun, 6 Aug 2000, Carlos Carvalho wrote: > >>Does this patch allow raid5 over raid0? That'd be really wonderful... > >Despite it's useful nor not, which 2.?.x? The latest if possible, but the one your patch applies to if I have no other choice... >In 2.2.x that's not possible but for _very_ silly reasons. So can't this be fixed? >On 2.4.x we now have a modular and recursive make_request callback, that >will allow us to handle all the volume management layering correctly (so >if raid5 on top of raid0 isn't working right now in 2.4.x send a bug >report ;). Yes, but it's useless because of the abysmal (absence of) speed. And all the VM problems... The machine I need raid50 on is a central server, if it stops everything else goes down. In fact I'm not using 2.4 on it precisely because of the VM/raid problems!! :-( :-( If I can't do raid50 on our server I'll have to resort to raid10, losing 50% of our so expensive disks...
Re: raid-2.2.17-A0 cleanup for LVM
On Sun, 6 Aug 2000, Carlos Carvalho wrote:
>Does this patch allow raid5 over raid0? That'd be really wonderful...
Despite it's useful nor not, which 2.?.x?
In 2.2.x that's not possible but for _very_ silly reasons.
Raid0 in general is a no brainer and fully transparent layer that we can
place anywhere/anytime we want, definitely also behynd raid5. Fixing this
in 2.2.x is ugly (it's just ugly enough supporting LVM (lvm does linear
and raid0) on top of RAID{[015],linear} ;). (note the other way around
doesn't work for the same silly reasons raid5 on top of raid0 doesn't
work) Other raids (1/5) that needs to generate additional requests are a
little bit more problematics though.
On 2.4.x we now have a modular and recursive make_request callback, that
will allow us to handle all the volume management layering correctly (so
if raid5 on top of raid0 isn't working right now in 2.4.x send a bug
report ;).
Andrea
Re: raid-2.2.17-A0 cleanup for LVM
Chris Mauritz ([EMAIL PROTECTED]) wrote on 6 August 2000 22:17: >> Does this patch allow raid5 over raid0? That'd be really wonderful... > >Huh? What do you mean by that? Raid 5 is essentially Raid 0 with the >parity bits spread out across all the drives. Running one on top of >the other (like 0 + 1) doesn't make any sense. It does. Instead of having disk partitions making up the raid5 you have raid0 arrays. Very useful for making raid5 out of disks of different sizes and some other very useful things. I've just tried raid5 over raid0 with 2.2.17pre13 and it doesn't work, even with the raid0 components being on different disks (two raid0 on different disks, composed of 3 partitions).
Re: raid-2.2.17-A0 cleanup for LVM
> From [EMAIL PROTECTED] Sun Aug 6 21:45:04 2000 > > Andrea Arcangeli ([EMAIL PROTECTED]) wrote on 3 August 2000 19:55: > >>On Aug 2, 7:12pm, Andrea Arcangeli wrote: > >>} Subject: raid-2.2.17-A0 cleanup for LVM > >> > >>> This patch cleanups the new raid code so that we have a chance that LVM on > >>> top of RAID will keep working. It's untested at the moment. > >>> > >>> >ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.2/2.2.17pre13/raid-2.2.17-A0/raid-lvm-cleanup-1 > > Does this patch allow raid5 over raid0? That'd be really wonderful... Huh? What do you mean by that? Raid 5 is essentially Raid 0 with the parity bits spread out across all the drives. Running one on top of the other (like 0 + 1) doesn't make any sense. Even if you could get it to work, it would be slower than a simple RAID 5 array, don't you think? Cheers, C -- Christopher Mauritz [EMAIL PROTECTED]
Re: raid-2.2.17-A0 cleanup for LVM
Andrea Arcangeli ([EMAIL PROTECTED]) wrote on 3 August 2000 19:55: >>On Aug 2, 7:12pm, Andrea Arcangeli wrote: >>} Subject: raid-2.2.17-A0 cleanup for LVM >> >>> This patch cleanups the new raid code so that we have a chance that LVM on >>> top of RAID will keep working. It's untested at the moment. >>> >>> >ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.2/2.2.17pre13/raid-2.2.17-A0/raid-lvm-cleanup-1 Does this patch allow raid5 over raid0? That'd be really wonderful...
Re: raid-2.2.17-A0 cleanup for LVM
On Thu, Aug 03, 2000 at 07:55:18PM +0200, Andrea Arcangeli wrote: > On Thu, 3 Aug 2000, G.W. Wettstein wrote: > Grab 2.2.15aa1 or 2.2.17pre11aa2, they have completly reliable LVM (I also > switch between it and 2.4.x stock without changing anything). It can be > used for production. You can find the separate patches that compose that > kernel in the ftp site as well. strange i was never able to run lvm on top ov raid with 2.4 the lvm tools just don't guess what an md device is :( L. -- Luca Berra -- [EMAIL PROTECTED] Communication Media & Services S.r.l.
Re: raid-2.2.17-A0 cleanup for LVM
On Thu, 3 Aug 2000, G.W. Wettstein wrote: >On Aug 2, 7:12pm, Andrea Arcangeli wrote: >} Subject: raid-2.2.17-A0 cleanup for LVM > >> This patch cleanups the new raid code so that we have a chance that LVM on >> top of RAID will keep working. It's untested at the moment. >> >> >ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.2/2.2.17pre13/raid-2.2.17-A0/raid-lvm-cleanup-1 > >What are people using for LVM code on 2.2.1[67]? Grab 2.2.15aa1 or 2.2.17pre11aa2, they have completly reliable LVM (I also switch between it and 2.4.x stock without changing anything). It can be used for production. You can find the separate patches that compose that kernel in the ftp site as well. Andrea
Re: raid-2.2.17-A0 cleanup for LVM
On Aug 2, 7:12pm, Andrea Arcangeli wrote: } Subject: raid-2.2.17-A0 cleanup for LVM > This patch cleanups the new raid code so that we have a chance that LVM on > top of RAID will keep working. It's untested at the moment. > > >ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.2/2.2.17pre13/raid-2.2.17-A0/raid-lvm-cleanup-1 What are people using for LVM code on 2.2.1[67]? The only thing that I have found reliable was a port of the 8i stuff that a gentleman created which he said he was submitting to Heinz for approval. I had to couple this with the 2/10/1999 toolset in order to get a complete system. I have been using this in a limited production environment but considering the pathway to it I have been reluctant to really put the system under stress. The LVM code looks very promising and well-done and essential to those of us in production environments. There doesn't appear to be a clear path to follow for those of us working with late 2.2.x kernels. I tried merging the LVM patches that I am using with the 2.2.16 RAID patchset but there is a massive collision in ll_rw_blk.c file that doesn't appear to be straight forward in its resolution. > Andrea Greg }-- End of excerpt from Andrea Arcangeli As always, Dr. G.W. Wettstein, Ph.D. Enjellic Systems Development, LLC. 4206 N. 19th Ave. Specializing in information infra-structure Fargo, ND 58102development. PH: 701-281-4950WWW: http://www.enjellic.com FAX: 701-281-3949 EMAIL: [EMAIL PROTECTED] -- "If you think nobody cares if you're alive, try missing a couple of car payments." -- Earl Wilson
