Help, my disk array has one dead member

[Liam Proven]

On 26 March 2017 at 16:00, Xen <list at xenhideout.nl> wrote:
>
> Windows cannot include RAID on the boot disk.

So?

> I guess I am wrong about it, the Microsoft Dynamic Disks page is a morass
> without much clear information. It was said that Windows 7 cannot boot from
> a dynamic disk with more than 1 volume.

Part of the reason is that the "Dynamic Disks" functionality in
Windows 2000 Server and later isn't Microsoft code. It is a
licensed-in version of the Veritas storage manager.

http://archive.is/NR6k

Windows NT 3 & 4 had home-grown software RAID.

> If I converted this disk to dynamic I would lose the Linux partition on it
> ;-). I don't know what would happen to it. There is so much unclarity. I
> guess Linux can read dynamic disks? There is GRUB code that handles them.

I think so. I haven't tried and would not recommend it.

> There is probably no cross-platformness whatsoever regarding the RAID part.
> I wonder if I can create a Windows Dynamic RAID and then turn one of the
> subvolumes into LVM raid.

Doubt it. I *definitely* would not try it.

> A Windows Dynamic disks basically no longer has a partition table, right.

Yes, same as a GPT disk.

> In other words, I just wonder if I can still have any Linux partitions
> inside a Dynamic Disk.

I think Linux can read it but possibly not make Linux-native
partitions inside it. I don't know, I have not and would not try
except for experimental research.

> At least this was true for Windows Server 2008. It is hard to find updated
> information.

That's essentially the Server edition of Vista. Server 2008 R2 was
Windows 7 Server.

Windows 8 and later replace the Veritas code with a new in-house LVM
system called Storage Spaces.

https://blogs.msdn.microsoft.com/b8/2012/01/05/virtualizing-storage-for-scale-resiliency-and-efficiency/

> See I just think the entire Windows solution is a big mess.

It is somewhat coherent inside its own space.

Do not mix Windows LVM with Linux LVM. In fact, in general, do not mix
advanced storage (any of them, ZFS, LVM, XFS, JFS, Veritas, anything)
on the same physical drive. At all, ever.

> If GRUB can actually read LDM partitions than I'm sure I can boot from it in
> Linux, but can Linux also read those partitions? In other words, can I
> create whatever I like out of a LDM volume and have Windows not interfere
> with it?

Don't know. Don't even try.

> You realize those RocketRAID cards sell for some €100 to €130 euros right
> (or more).

Yes. Cheap. Also crappy. Do not use.

For hardware RAID, controllers, look at adding a zero to that price.

>> DO NOT USE FIRMWARE RAID IN LINUX. AT ALL, EVER, UNDER ANY CIRCUMSTANCES.
>
>
> All of your screaming isn't going to do much good. If it's the only way to
> be cross-platform.

It is never the only way.

Do not do it. You are _asking_ to lose data.

> Hardware cards as well as firmware BIOS typically have superior user
> interfaces. The AMD software was also exceptionally good, it just bugged out
> in the most important operation. I haven't seen anything from Linux that was
> really friendly; the mdadm interface is worse than what existed before; you
> can't use it witout a cheatsheet telling you what to do.

This stuff is complicated. You are doing things that are complicated.
If you can't handle that, then don't do it. Buy a cheap NAS like a
Synology or something and let it worry about it for you.

For lower-budget clients, I have successfully used devices such as
Thecus to inexpensively attach a few terabytes of RAID to a
peer-to-peer LAN:

http://www.thecus.com/product.php?PROD_ID=8

> (I have successfully used a
> I am running (well, it is not doing anything) an mdadm Linux system that I
> once installed using the Debian installer that can support these
> configurations. I have NO clue what to do if anything breaks. I would have
> to look it up first.
>
> So ehm. Linux software raid would be awfully nice if it was actually usable.

I've been using it for 20 years, both on my own systems and on live
customer ones. It works fine. It isn't easy, no, but neither is
walking a tightrope between the 2 towers of the Petronas building. (I
was going to say the World Trade Centre, as Philip Petit actually did
that, but it's not there any more.)

With asking to do this with dual-boot, you are asking to ride a
unicycle across it. And if you want to mix 2 different software RAID
systems, you are asking to do it blindfolded.

Don't.

I am not claiming to be an expert. I have done it and still have live
systems using it now. I know what I'm talking about.

Don't.

> I would try (and I might try) (and I will try) LVM RAID which is almost the
> same as regular mdadm software RAID now.

But more difficult, in my direct personal experience.

> LVM is just a bitch to work with if you do the more advanced stuff as well.
> They also don't care *too* much about fail-safe operation.

I don't recommend Linux LVM at all, to be honest. If I wanted such
advanced storage, I'd look to ZFS, probably, and today that means
using TrueOS, i.e. FreeBSD.

Or, if the customer has the budget, a NetApp or some other grown-up
storage solution.


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