Striping and Mirroring on Linux???

Striping and Mirroring on Linux???

Post by John M. Brow » Fri, 28 Mar 1997 04:00:00



Can you strip and or mirror volumes under Linux???
If so what is needed?


 
 
 

Striping and Mirroring on Linux???

Post by Ross Irvi » Mon, 31 Mar 1997 04:00:00



: Can you strip and or mirror volumes under Linux???
: If so what is needed?
:

Mirroring shouldn't be that difficult, but if your talking stripping,
then your talking RAID 5. Raid 5 in a software solution would not only
bog down your system, but wouldn't be reliable...

If your are really worried about your data enough to consider raid X,
then get a hardware solution.

Regards..

--

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Striping and Mirroring on Linux???

Post by Jon Martin Solaa » Mon, 31 Mar 1997 04:00:00




> : Can you strip and or mirror volumes under Linux???
> : If so what is needed?
> :

> Mirroring shouldn't be that difficult, but if your talking stripping,
> then your talking RAID 5. Raid 5 in a software solution would not only
> bog down your system, but wouldn't be reliable...

Linux supports raid 0 and raid 1. Raid 0 is refered to as
striping. It is still in beta, but I have heard people are running
striped disks without any trouble, and with an increase in speed.
Raid 1 is alpha software and provides mirroring.

Here is what the author, Marc ZYNGIER, writes:
--------8<--------8<--------8<--------8<--------8<--------8<--------8<
Linear means that real devices are appended to each other.  This kind
of device should be easily expandable (see 'Future extensions'
section), but gives little or no speed improvement.

Raid0 does a classic (and rather efficient) striping on disks
(i.e. contiguous blocks on the md device are spread across real
devices).  It gives rather good performances on SCSI disks, specially
with concurrent disk access.  There's no limitation on disks sizes
(i.e. sizes can be different, md will cope with this).

Raid1 adds mirroring to raid0 striping.  Note that it is not complete
yet (no rebuild tools, error trapping is incomplete).  It's also known
to be rather slow when writing.

        Please note that, since all of this is done by software, it
can't be as fast as a hardware implementation of these RAID levels.
You can even say that it is rather slow.  Anyway, it is better than
nothing at all...
--------8<--------8<--------8<--------8<--------8<--------8<--------8<

--
Jon Martin Solaas

 
 
 

Striping and Mirroring on Linux???

Post by Brian Cas » Mon, 31 Mar 1997 04:00:00


Wait a minute...RAID-0 is disk striping (not stripping), is supported by
the
multiple-devices Linux driver (md), and works for me just fine. I setup
a 2-disk stripe set (the two partitions can even be unequal in size) and
got about 40% faster performance on one benchmark. Haven't done
much testing yet, though.

bcase




> : Can you strip and or mirror volumes under Linux???
> : If so what is needed?
> :

> Mirroring shouldn't be that difficult, but if your talking stripping,
> then your talking RAID 5. Raid 5 in a software solution would not only
> bog down your system, but wouldn't be reliable...

> If your are really worried about your data enough to consider raid X,
> then get a hardware solution.

> Regards..

> --

> Computer Science Department,     Phone GSM : +61 419 565 232
> RMIT, Melbourne, Australia.      Nokia 2110 FAQ Creater, see below for
WWW.
> Novell Network Admin - V.B.R.    Work : +61-3-9349-2744 Fax:
+61-3-9349-2711
> CNE in progress.                 WEB :

http://yallara.cs.rmit.edu.au/~rwi/

- Show quoted text -

Quote:> Any Spam E-mail will be returned * 1000 -- You have been warned.

 
 
 

1. Veritas striped-mirror (Striped Pro) question

Ok,

I am trying to create a striped-mirror here on an A5200 array with 22 16.9g
drives in it.  I have never used a striped-mirror before so I want to make
sure I get it right the first time (hence this email).  I used the first two
disks on each controller (one as the root disk the other as the root mirror)
and the next 9 disks on each controller I want in a raid 1+0 config (the
last disk on each controller being a hotspare).  I want this to be one large
partition to store a database on (152gb).  I will be using standard DRL
(writes are not always sequential so I want to avoid any IO hosing such as
that you can get with drlseq.  I would like to mirror it like this:

c0t17--c0t18--c0t19...c0t25--c0t26 - controller one (c0)
    |           |           |           |           |
   m         m         m         m         mirrors to
    |           |           |           |           |
c2t01--c2t02--c2t03...c2t08--c2t09 - controller two (c2)

Would the following command be correct to create it with DRL enabled and
mirror it in the fashion i stated above?

vxassist -o ordered -g vsnt01 make vsnt 152g layout=striped-mirror
logtype=drl nmirror=2 ncol=9 c0t17 c0t18...c0t26 c2t01 c2t02...c2t09

(where vsnt01 is the diskgroup name and vsnt is the partition i want to lay
out)

also, do you guys have any preferences on the stripewidth or will the
default do fine for an array this size?  Any other recommendations would be
appreciated.  Thanks.

Michael J. Ayers

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