Re: RAID framework?

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

Gabriel Ambuehl wrote:

> Hi,
> are there any plans to incorporate a better RAID framework (I don't
> like vinum at all, you can't boot from it and it's hideously complex to
> use) or even full blown volume manager into Dragonfly? 

Grusse, Gabriel,

There has been some recent discussion of something similar to IBM's
'Logical Volume Manager'.  Not on the 'critical path' AFAICS, nor needs 
to be.

Browse the archives...

> In a lot of
> situation, good software RAID would be much more flexible than
> controller based implementations, especially if there was RAID5 with
> support for the addition of new disks.

RAID5 is a massive resource-hog w/o 'fully independent' hardware 
controllers,
hardware XOR, dedicated hardware CPU or "I/O processor", cache RAM, etc.

Look at what it has to do w/r distributed parity or ECC to insure 
recoverability.
Asking a lot to have that done w/o its own CPU/SPC as well as other 
resources.

> Reason for me asking is a lot of weird issues with FreeBSD5 on my
> current fileserver using 3ware cards at home...

. .. by no means limited to 3Ware!

[S | P]ATA 'RAID' in general is still limited to either very expensive
hardware for data warehousing, or 'let's pretend' for consumer market.

- Not much yet available that is both affordable and effective for a
mere 1U or 2U server. Even the one IBM is using is weak.

> Regards,
> Gabriel

I haven't yet found anything for SATA that looks better (on paper anyway)
than the new'ish LSI MegaRAID, but cheap they are not, and only Linux 
drivers
are listed so far. 'if only..' they emulated SCSI and used existing SCSI 
drivers at the
 system side, as a couple of (now rare/discontinued?) others did....

 - now there's a coding project for you...

If you will commit to porting / re-writing / creating new (haven't 
looked at their license)
 a DragonFly driver, I'll ship you a controller.

It would be nice if you can also match the mere 8KB driver footprint
of the ASUS DA-2/3XXX dual-channel SCSI RAID series....

Bill