Setting up a RAID array?

EDIT because I read too fast and didn't see you want a RAID1...

yeah it looks good, so long as you can live with RAID3 only. if you get one, i'd appreciate you letting me know how it goes. im looking at buying one early next year..

if you need more speed, and RAID5/6 try their G-Speed. takes 6 drives and connects via either FibreChannel or UltraSCSI320

Kingsly said:

What's the difference between RAID 3 and 5? They both stripe and are both redundant, right?

Click to expand...

Hello,

A RAID 3 uses byte-level striping with a dedicated parity disk, wheras A RAID 5 uses block-level striping with parity data distributed across all member disks.

In esscense they are the same, but one RAID 5 is more efficient.

but one RAID 5 is more efficient

Click to expand...

could you define "efficient"?

they both provide N-1 protected space. ie: 5 disks will give u Disk size x 5 - 1 in storage space.

In the event of a disk failure, RAID3 maintains the same access speed, whereas RAID5 is slower.

Under normal operations, RAID5 supports multiple operations at once, whereas RAID3 essentially cannot do this, because the heads are all moved in-sync..

pengu said:

could you define "efficient"?

Under normal operations, RAID5 supports multiple operations at once, whereas RAID3 essentially cannot do this, because the heads are all moved in-sync..

Click to expand...

You answered it yourself.

that isnt efficiency really, its the ability to have multiple concurrent accesses to the disk. if you dont need multiple concurrent accesses, it is not more efficient. for things that have large continuous reads/writes, RAID3 should be a better choice, because in the event of a failure, the media is still accessible at the same speed.

Whatever, we don't need to be arguing about the definition of "efficient" ... but yeah I was just telling him which I would prefer, and that's RAID 5.

I would like RAID5 too, but there are very few (elegant) options for TRUE hardware RAID5 using SATA/SATAII disks, that are supported on Macs.

I use an old G3 powermac with an 8port sata raid card (RocketRaid 2220) for RAID5 over 4 disks.

I reccomend an old G4 powermac if you go down the same route (built in gigabit ethernet, more bays, bigger powersupply, better bus)

having run an older g4 (400mhz) as a local server for a while, i wont be taking that option any time soon.

it was noisy, slow, and a pain to manage. if you want RAID5, (with the simplicity of the G-Tech box) i suggest either a G-Speed (does RAID 6 too) with either a SCSI or FC card, or a Kano Desktop X-Spand unit with a RocketRaid 2224 (for PCI-X, not sure what the equivelant PCI-E card is)
-edit:
the RocketRaid 2322 has 2 external Mini-SAS connectors, which can be (with a Mini-SAS-> Infiniband cable) used in a PCI-E system.

both are simple, 1 cable setup (2 cables for FC i think, if u want increased bandwidth). the G-Tech G-Raid-PRO has the advantage of simply "plug it in", without the need for extra cards.

G-Tech initially announced the G-Raid-Pro would support RAID5, but it never eventuated

Kingsly said:

I was thinking about doing that to my PM G4, but its got a busted ATA controller

I suppose it will work, because it still sees the master drive, just not a slave.

Click to expand...

You don't need a working ATA controller. The RAID card will manage the disks for you.

If your G4 still sees the master, you could use that for the boot drive, and let the RAID array focuss on its own thing.

pengu said:

having run an older g4 (400mhz) as a local server for a while, i wont be taking that option any time soon.

it was noisy, slow, and a pain to manage. if you want RAID5, (with the simplicity of the G-Tech box) i suggest either a G-Speed (does RAID 6 too) with either a SCSI or FC card, or a Kano Desktop X-Spand unit with a RocketRaid 2224 (for PCI-X, not sure what the equivelant PCI-E card is)
-edit:
the RocketRaid 2322 has 2 external Mini-SAS connectors, which can be (with a Mini-SAS-> Infiniband cable) used in a PCI-E system.

Click to expand...

Fair enough, tho these external RAID5 boxes were way out of my budget.

£500 for a 4 port RAID5 box vs £50 for a second hand G3 plus £150 for a cheap Rocketraid 2220.

Another point, if you're going to access it over ethernet, there's no point going for a RAID box or card that can go at greater than gigabit ethernet speeds.

Final point: These Rocketraid cards that will work in a G3 or G4 powermac will not work in anything newer - they are PCI/PCI-X cards.

Pretty much all new PCs and Macs use PCIe. So if you buy a PCI-X raid card for an older PC or powermac, accept that it's gonna stay there - you won't be able to transplant it to a G5 at some point in the future.

I'm happy with my G3 RAID5, tho I do plan to transplant it to a decent G4 powermac when these become cheap enough on the market.

Another point, if you're going to access it over ethernet, there's no point going for a RAID box or card that can go at greater than gigabit ethernet speeds.

Final point: These Rocketraid cards that will work in a G3 or G4 powermac will not work in anything newer - they are PCI/PCI-X cards.

Pretty much all new PCs and Macs use PCIe.

Click to expand...

ok. the original post said it was for FCP. this makes me think it WONT be used over ethernet, and SPEED is important here.

as for PCI cards. only the last series of G5's have PCI-E slots. everything up to the dual-core (ie, G5 Quad) models has PCI-X (or PCI on the "crippled" models).