Re: Best software raid 5 software?

2007-03-21 Thread Peter A. Giessel
On 2007/03/21 6:33, John Nielsen seems to have typed:
> On Wednesday 21 March 2007 03:03:53 am Gabriel Rossetti wrote:
>> I am about to switch to software raid 5 for my personal server. I know
>> hardware raid 5 is better, but being a student I'd rather not invest in
>> a raid adapter now, plus my cpu is being used at about 0.0% 24/24 7/7,
>> so it needs some exercise :-)
>>
>> I've heard of several software-based raid-5 projects, mainly of Vinum,
>> has anybody tested it or any other ones?
>> Which would you suggest?
> 
> As far as I know, gvinum is the only software package in FreeBSD that can do 
> RAID 5. The initial learning curve is a bit steep, but it should work fine 
> once you get it configured.

There is also a geom_raid5 class, which you can find out about by
searching the freebsd-geom mailing list:
http://www.freebsd.org/cgi/search.cgi?words=graid5&max=250&source=freebsd-geom
I don't think its quite ready for prime-time though.

Vinum did not make the transition to Gvinum as cleanly as could be
desired, so if you setup a gvinum array, I would recommend keeping good
backups and testing it pretty harshly to make sure it will cleanly
survive a drive failure.  Gvinum has been getting significantly better
with time, but as with anything before putting it into a production
environment, test it throughly (and keep good backups, did I mention
that keeping good backups is important?  Because good backups are
important...)
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Re: Best software raid 5 software?

2007-03-21 Thread John Nielsen
On Wednesday 21 March 2007 03:03:53 am Gabriel Rossetti wrote:
> I am about to switch to software raid 5 for my personal server. I know
> hardware raid 5 is better, but being a student I'd rather not invest in
> a raid adapter now, plus my cpu is being used at about 0.0% 24/24 7/7,
> so it needs some exercise :-)
>
> I've heard of several software-based raid-5 projects, mainly of Vinum,
> has anybody tested it or any other ones?
> Which would you suggest?

As far as I know, gvinum is the only software package in FreeBSD that can do 
RAID 5. The initial learning curve is a bit steep, but it should work fine 
once you get it configured.

I would also suggest that you look at graid3 which, not surprisingly, supports 
RAID 3. As you may or may not know, RAID 3 is very similar to RAID 5. You get 
S*(N-1) usable space, where S is your disk size and N is the number of disks. 
You need at least three disks but can use more. Both allow you to lose any 
single disk and not lose any data. The difference is that RAID 5 stripes the 
redundant parity data across all of the disks and RAID 3 uses a single disk 
for all parity writes. As a result, RAID 5 potentially offers somewhat better 
read performance if disk I/O is the bottleneck (and assuming each disk has 
its own controller/I/O path). In the case of software raid and commodity 
(non-server) hardware, the difference should be nominal.

Other software RAID options include gmirror (recommended for RAID1), gstripe 
(recommended for RAID0, can be combined w/ gmirror), ataraid (supports RAID0, 
RAID1, JBOD, and combinations on ata controllers only), and ccd (supports 
RAID0, RAID1, and JBOD; largely deprecated by gmirror and gstripe).

JN
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Best software raid 5 software?

2007-03-20 Thread Gabriel Rossetti

Hello,

I am about to switch to software raid 5 for my personal server. I know 
hardware raid 5 is better, but being a student I'd rather not invest in 
a raid adapter now, plus my cpu is being used at about 0.0% 24/24 7/7, 
so it needs some exercise :-)


I've heard of several software-based raid-5 projects, mainly of Vinum, 
has anybody tested it or any other ones?

Which would you suggest?

Thank you,
Gabriel

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