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mzyou
05-Jul-2013, 10:55
Hi,

In the section 17.1.3. Setting Up Storage-based Protection of doc <SLE-ha-guide>, it says:

The shared storage segment must not make use of host-based RAID, cLVM2, nor DRBD*.
However, using storage-based RAID and multipathing is recommended for increased reliability.

And, from the https://en.wikipedia.org/wiki/RAID, I only see below types of RAID:

Hardware-based RAID
Software-based RAID
Firmware/dirver-based RAID


So, I do not know what type is host-based RAID and storage-based RAID.

And what's problem will be caused by "host-based RAID"?

Thanks!

bwisupport
05-Jul-2013, 13:15
As I understand 'host-based'is when the OS sees two or more disks and
builds a RAID Array from these with OS-Tools (aka softraid). Storage
based with multipathing is a SAN-Mirror where the OS knows multiple
pathes to the storage (build by at least one fc-switch and two HBAs
connected to that switch). So if one HBA fails, multipathing will use
the other to connect to the storage. For more redundancy, you will often
use 2 mirorred SANs, each with 2 fc-switches an at least 2 HBAs per
Server...

Tom

mzyou
08-Jul-2013, 01:40
Hi,

Thanks for your answer! So, seems the "host-based" is "software-based", the "storage-based" is "hardware-based".

David Gersic
08-Jul-2013, 17:00
On Mon, 08 Jul 2013 00:44:05 +0000, mzyou wrote:

> Thanks for your answer! So, seems the "host-based" is "software-based",
> the "storage-based" is "hardware-based".

Yes, that's how I would interpret the descriptions.


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summitflier
11-Jul-2013, 23:13
Hostbased is usually a RAID controller in your PC/Server that is controlling the local disks (also in your PC).
(This can be hardware or software based)

Storage based RAID is normally on a NAS or SAN, disk array. The RAID controllers live on the disk array, not on your PC/Server.

A major disadvantage of host-based vs storage based, is redundancy. You probably only have 1 single RAID controller (in any)
in your PC, now sometimes these can be a PCI card, so you could install another one in another PCI slot, but even then you can't
usually use them to control the same group of RAID disks.

If you use HBAs to do fiber connections back to SAN array (usually these go through a fiber switch (like an EMC/Brocade for example)
the big advantage is you can either do active-active and theorectically double your disk I/O bandwidth, or you can do active-passive,
that way if one of your HBAs fail, you can still up on the other (fail-over) HBA.

I'm over-simplifying this down to a few paragraphs. But from what I gather, it's talking about a SAN (or possibly NAS) disk array,
rather than a group of disks controlled by a RAID controller physically in your server.

mzyou
17-Jul-2013, 09:50
Hostbased is usually a RAID controller in your PC/Server that is controlling the local disks (also in your PC).
(This can be hardware or software based)

Storage based RAID is normally on a NAS or SAN, disk array. The RAID controllers live on the disk array, not on your PC/Server.

A major disadvantage of host-based vs storage based, is redundancy. You probably only have 1 single RAID controller (in any)
in your PC, now sometimes these can be a PCI card, so you could install another one in another PCI slot, but even then you can't
usually use them to control the same group of RAID disks.

If you use HBAs to do fiber connections back to SAN array (usually these go through a fiber switch (like an EMC/Brocade for example)
the big advantage is you can either do active-active and theorectically double your disk I/O bandwidth, or you can do active-passive,
that way if one of your HBAs fail, you can still up on the other (fail-over) HBA.

I'm over-simplifying this down to a few paragraphs. But from what I gather, it's talking about a SAN (or possibly NAS) disk array,
rather than a group of disks controlled by a RAID controller physically in your server.

Understand, thanks a lot!