Raid: more than 4 drives? + Raid5 question

[copenhagen69]

Looking into raid5 for my htpc build coming soon. My question is this, on-board raid can only handle 4 drives correct? If I go for more I would need a raid card, right?

raid5 question:

I am thinking my system would need about 6 drives total. I wouldnt buy all 6 at one time, but I could keep adding drives to the array couldnt I? Say I buy 4 and a month later add another one. That would work, correct?

 

[TheoneandonlyMrK]

It would depend on the config of the raid array,s, you wouldnt be able to add drives if using the raid functionallity of your mobo ie sata set to RAID then config a raid array then install windows but, if set to AHCI then install windows and use their Rapid storage tec soft upto ver 10.5 is out, you could then easily add drives on the fly into the raid array using storage tool under the admin control panel.
I hadnt heard of the 4 disk limit either though i only went as high as 4 disk raid due to diminishing returns(after 3 the read write increases are small and cpu overhead larger) but have used 5 disks in 2 raid arrays in the same system so you may be fine there

If configured as above it would be raid in software mode technically which isnt quite as fast as hardware assisted raid but the difference isnt that much imho

 

[copenhagen69]

hmmm, I always thought 4 was the limit on raid for mobos? Maybe I dreamed it and then always believed it lol

OK, sweet, the AHCI with rapid storage tec soft sounds like the route I would go then ... I am not after fast read/write. It will be in my HTPC so I want redundancy so I will not lose all my movies/songs or whatever is on there.

 

[FordGT90Concept]

It should be able to RAID as many drives as there are ports are on the same controller but, check the mainboard manual to be certain.


There's always the advantage of portability with RAID cards though. Good 8-port RAID cards aren't cheap though.

 

[copenhagen69]

no they are not lol I wonder why they are so much. price on them has not seemed to dropped all that much lately

 

[Disparia]

Because there is onboard RAID and there is high-end RAID. Onboard has been taking over the mid-range as performance has improved significantly since the early days.

When a situation calls for more than onboard - then you gotta pay

 

[copenhagen69]

Because there is onboard RAID and there is high-end RAID. Onboard has been taking over the mid-range as performance has improved significantly since the early days.

When a situation calls for more than onboard - then you gotta pay

so I can raid as many hard drives as there is sata ports then? right?

 

[Disparia]

Short answer, yes.

Long answer, yes, but how you'd go about it depends on some things. Do you already have a board/chipset in mind? EFI BIOS or not? Would the board have extra ports for a boot drive or not?

 

[lilhasselhoffer]

The only limit to the number of drives in a raid is the amount of SATA connections the raid controller has. You may see boards with 8 SATA ports, but only capable of 6 drives for the raid (like my board). This is due to the other SATA being connected via a different chip.

I currently have an atom board running 5 2TB drives in raid 5. It isn't going to break any networking speed records, but it works just fine under windows 7 (GPT partition).

 

[copenhagen69]

Short answer, yes.

Long answer, yes, but how you'd go about it depends on some things. Do you already have a board/chipset in mind? EFI BIOS or not? Would the board have extra ports for a boot drive or not?

I was thinking more along the lines of an AM3 board .. not trying to build some super HTPC. I will play only movies about 95% of the time.

So I was thinking some cheap AM3 mobo with 5-6 sata ports and raid 5 support would be just fine. probably a lower power dual or tri core cpu

can the boot drive not be built into the raid5? if not, then I will just have a small sata drive for the OS and programs to run the movies ...

The only limit to the number of drives in a raid is the amount of SATA connections the raid controller has. You may see boards with 8 SATA ports, but only capable of 6 drives for the raid (like my board). This is due to the other SATA being connected via a different chip.

I currently have an atom board running 5 2TB drives in raid 5. It isn't going to break any networking speed records, but it works just fine under windows 7 (GPT partition).

ah ok .. that is what I was hoping. I am not after blazing speed. I just want secure storage and for it to run my HD movies perfect.

 

[theeldest]

Is this going to be running Windows or Linux? If it's Linux you can use full on software RAID via md. md will let you span an array across the onboard controller and dedicated cards. And the performance is actually pretty darn good. (there are some instances where md gives better performance than a dedicated card).

*none of this applies to Windows.

 

[copenhagen69]

Yes win7 media center

I was thinking something along the lines of ....


MSI 760GM-P33 AM3 AMD 760G Micro ATX AMD Motherboard
$59.99 -$5.00 Instant $54.99

AMD Athlon II X2 250 Regor 3.0GHz Socket AM3 65W Dual-Core Desktop Processor ADX250OCGMBOX
$60.99 $60.99

G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Dual Channel Kit Desktop Memory Model F3-10600CL9D-4GBNT
$39.99 $39.99

SAMSUNG Spinpoint F4 HD204UI 2TB 5400 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
$89.99 -$10.00 Instant $159.98

SAMSUNG Black Blu-ray Drive SATA Model SH-B123L/RSBP LightScribe Support (Retail)
$74.99 -$10.00 Instant $64.99

Subtotal: $380.94

 

[theeldest]

That's actually very similar to the hardware I've got in my HTPC (except it's running Ubuntu with XBMC).

The only thing I'd consider is dedicated graphics or better integrated if you're doing Blu-Ray. I've got the 785G board and the Radeon 4200 handled Full HD flawlessly. But I can't remember how much of an improvement over the 3000 it is. Have you looked into that?

 

[copenhagen69]

ya, I will have a dedicated card in there just so there is no snags... I have plenty laying around so that is not a worry.

XBMC looks awesome too. I may pick that up.

 

[Disparia]

I was thinking more along the lines of an AM3 board .. not trying to build some super HTPC. I will play only movies about 95% of the time.

So I was thinking some cheap AM3 mobo with 5-6 sata ports and raid 5 support would be just fine. probably a lower power dual or tri core cpu

can the boot drive not be built into the raid5? if not, then I will just have a small sata drive for the OS and programs to run the movies ...

On a non-EFI Intel board I'd create two arrays using the same disks (Matrix RAID). A small RAID-0 or RAID-5 less than 2TB (keep in mind future drives) and RAID-5 with the remaining space. That way I'd have that first array for a bootable MBR partition and the other GPT. After adding a disk or two, allow the arrays to rebuild, could expand out my partitions and all is good.

The ACHI/Storage Manager method mentioned earlier may work, I've never tried it.

But on AMD? Well, I don't do much with AMD concerning RAID. I'll leave that for someone else

 

[copenhagen69]

Hmmm, I like that idea of make 2 seperate raids for the OS then dvd storage

is intel and AMD that much different when it comes to raids?

 

[TheoneandonlyMrK]

ive never raided on AMD, im presently on soft raid and have used MOBO raid mostly and this is the easiest to setup and the only one you can easily add disks too and yes you could still do multiple raid arrays either way

also of note is that with mobo and soft raid(more mobo i found) OCing the fsb/cpu increases though slightly read write speeds to a point but worth about 30 Mbps on 4 disk raid similar with 3, all in all though 3 disks in raid is the sweet spot either as 2x raid 0 + 1 mirrored or 3x raid 0 as i did i never mirror as i backup anything imporatant anyway on different drives

 

[FordGT90Concept]

no they are not lol I wonder why they are so much. price on them has not seemed to dropped all that much lately

Because they aren't "adapters," the are controllers. That is to say, they have their own processor and RAM instead of just an interface (meaning the CPU and system RAM does all the work). It's like comparing onboard audio to a quality audio card.



This board has 8 SATA (6 via AMD SB850, 2 via Marvell SE9123/9120). The eSATA port is hardwired to one of the Marvell connectors (SATA3_8) so you can't use both at the same time. You could have up to 6 HDDs configured in RAID5 on AMD SB850 and one DVD+/-RW drive on Marvell (SATA3_7). That would leave the eSATA/SATA3_8 port available.


MSI 760GM-P33 does not support RAID5. It has 6 SATA 3 Gb/s (SATA2) ports, all on AMD SB710. I prefer to keep everything not RAID'd on a separate controller because I have had issues running ACHI devices on controllers configured for RAID (said differently: I don't want to risk it).

is intel and AMD that much different when it comes to raids?

I imagine not. Basically you're going to see an option for "stripping (RAID0), mirror (RAID1), stripping+mirroring (RAID0+1), and stripping w/ parity (RAID5)" with lists for which drives to place in the array and which to leave out. I've only done RAID under Intel Matrix Storage, Highpoint RocketRAID, and NVIDIA nForce though (all very similar except RocketRAID is more involved because it's a card rather than onboard implementation).

 

[slyfox2151]

I imagine not. Basically you're going to see an option for "stripping (RAID0), mirror (RAID1), stripping+mirroring (RAID0+1), and stripping w/ parity (RAID5)" with lists for which drives to place in the array and which to leave out. I've only done RAID under Intel Matrix Storage, Highpoint RocketRAID, and NVIDIA nForce though (all very similar except RocketRAID is more involved because it's a card rather than onboard implementation).

i think the intel chipsets are better for raid IMO, i went from an ICH10r to this amd850? south bridge. its slower, latency seems to be an issue with it, bandwidth hasnt changed enough to say witch one is better in that regard. (upgraded from E7300 to this 1090T)

i will be moving to an off board raid controller.