[PVE-User] md installer?

Adam Hunt voxadam at gmail.com
Thu Jul 4 21:01:12 CEST 2013


While I would love to see softraid in PVE but the developers seem to be
dead set against it.

http://pve.proxmox.com/wiki/Software_RAID
http://forum.proxmox.com/threads/398-New-features
http://forum.proxmox.com/threads/838-Install-on-Soft-Raid
http://pve.proxmox.com/wiki/Storage_Model
http://forum.proxmox.com/threads/7112-Suggestion-integrate-block-level-SSD-caching-into-the-PVE-kernel

That's not to say it hasn't been done with previous versions of Proxmox.

http://www.howtoforge.com/proxmox-2-with-software-raid
http://www.petercarrero.com/content/2012/04/22/adding-software-raid-proxmox-ve-20-install

I haven't had a chance to try a custom install of PVE 3 on softraid (yet).
I do intend on doing it when I get some free time (ha!). The devs seem
pretty dead set against softraid and I'm not entirely clear why though
they're much more experienced with their codebase, I'm sure they have their
reasons. I haven't seen such an absolute attitude against softraid for
years. Linux's softraid implementation(s) are notoriously stable and out
perform hardware RAID on a regular basis. Also, many PVE users would like
to install it on leased or colo boxes that either don't support or don't
have room for an old school hardware RAID card. I personally am interested
installing PVE on a leased box at OVH with dual 1 gig hard drives where
they only support hardware RAID on extremely high end systems that are
massive overkill for a personal server.

--adam



On Thu, Jul 4, 2013 at 11:16 AM, Gerald Brandt <gbr at majentis.com> wrote:

> Does anyone know the reasons behind that decision?
>
> In my experience, Linux software RAID is exceptional in performance and
> stability.
>
> Gerald
>
>
> ------------------------------
>
> *From: *"Adam Hunt" <voxadam at gmail.com>
> *To: *"Paul Gray" <gray at cs.uni.edu>
> *Cc: *pve-user at pve.proxmox.com
> *Sent: *Thursday, July 4, 2013 12:46:58 PM
> *Subject: *Re: [PVE-User] md installer?
>
>
> My understanding was that PVE does not now and will never in the future
> support the softraid capabilities of Linux. If RAID is wanted than the only
> option is old-school hardware RAID.
>
>
> On Thu, Jul 4, 2013 at 5:29 AM, Paul Gray <gray at cs.uni.edu> wrote:
>
>> On 07/04/2013 06:30 AM, Paul Gray wrote:
>> > I think, I may be wrong, that the Barebone Installer is not
>> customizable at all, and won't be.
>>
>> The installer is configurable to the extent that any distribution's
>> installer iso is configurable.  You just need to know where the
>> installation components are and how they interact.
>>
>> The origin of my question to the list arises from the hints of md
>> support already in the places within the installation.
>>
>> After ISOLINUX expands the initrd and finds its proxmox iso image, the
>> init script invokes /sbin/unconfigured.sh on the ISO mount.
>>
>> In the final acts of /sbin/unconfigured.sh, there's a commented-out line
>> to shut off md device md0, indicating that there was once a time when it
>> was enabled.
>>
>> But there's quite a bit more: For example, after proxmox finds the
>> installation media and starts up X, the installation contiues from
>> openbox/.xinitrc to invoke /usr/bin/proxinstall.
>>
>> Within the /usr/bin/proxinstall script, one finds this code in the
>> probing for disks:
>>
>>     foreach my $hd (@$hds) {
>>         my ($disk, $devname) = @$hd;
>>         next if $devname =~ m|^/dev/md\d+$|;
>>         print "found Disk$disk N:$devname\n";
>>     }
>>
>> So the installer is specifically excluding md devices when looking for
>> disks.
>>
>> Naturally this begs the question of what would happen if one added
>> modprobe's for md raid support (right after the modprobe of dm_mod in
>> unconfigured.sh), removed the "next if..." line in the proxinstall
>> script above, reconstituted the ISO, and booted it up to "see what
>> happens."
>>
>> It seems that someone else had probably already done this.  If no one
>> else has done it then it's likely someone would be willing to offer
>> advice on why enabling support for md devices would be "a bad thing(tm)"
>> or at least offer some insight as to why md devices are specifically
>> avoided in the present installer.
>>
>> --
>> Paul Gray                                         -o)
>> 314 East Gym, Dept. of Computer Science           /\\
>> University of Northern Iowa                      _\_V
>>  Message void if penguin violated ...  Don't mess with the penguin
>>  No one says, "Hey, I can't read that ASCII attachment ya sent me."
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>>
>
>
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