HexiumVII

Your thoughts on Windows software RAID5 vs Nvidias Raid

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I'm thinking of making a RAID5 array with 4x500GB for a 24/7 fileserver i'm building. I'm debating whether to use Nvidias Raid or to use Windows Server hack for XP. I'm going to be using either a 680i or 965 with Core Duo. I've always heard Nvidias Raid being a bit iffy and often causing data loss and corruption. So i'm a bit scared to rely 1.5GB on it. As for the Windows it seems a bit crude, but it seems to work decently and it seems like you can just move the drives over to any other comp and have Windows Reinitiate the RAID from any controller, but it looks like you have to reinitiate the RAID after every reboot. What do you guys think?

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If write performance really matters to you, then you should forget about both Windows and on-board RAID 5.

Two options I'd suggest as alternatives to a really high-end storage controller for faster writes: (1) A decent middle-end storage controller such as a RocketRaid 2310. (2) Onboard Intel-based RAID 10.

You lose one additional drive's storage capacity with RAID 10, and considering the cost of this drive, it's about the same as a lower-end storage controller. A good RAID 10 will give theoretically and sometimes practically superior performance, but the rest of your network and systems will not be up the theoretical performance, so you should probably think about them as being roughly the same.

The nVIDIA 680i chipset is under some fire at the moment with SATA issues, so I'd avoid it for this role.

Also note that no single RAID system is an adequate substitute for a backup, and a full backup helps enormously for maintaining RAID, so you might be better off expanding this into two problems -- the storage server and a full (or at least a non-replaceable data) backup system.

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Some of the Nvidia 680 notherboards have corruption issues with the hard drives at the moment. 965 chipset performance is hit and miss depending on the board. Nforce4 is fine though and likly far far cheaper for file server use. For a file server I would recomend 0+1 if you feel you need raid or two seperate raid 0 or raid 1 arays. Raid 5 is best serverd with a high end controller and those dont come cheap.

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OK, so you want to use either XP software RAID or nVidia MediaShield.

Comparing the two:

1. XP Software RAID

Advantages:

- Is (much) faster than the nVidia one on nForce 5 with writes. I have no experience of the nForce 6 series however.

- Is independant of controller(s) and computer system(s). If the controller fails, just move the drives onto any other one.

Disadvantages:

- Some people argue that problems occur with regard to windows updates and/or service packs. I have never experienced this problem myself, but it is certainly possible. It is a hack after all.

- Slow writes compared to some hardware solutions (tops out around 60-80mB/sec on a Sempron 1.6)

- Very intolerant of intermittent HDD failures (if two drives transiently lose power at the same time, SRAID fails the array with no option for recovery, even if both drives are later reconnected and work fine)

- Automatically rebuilds every time the system is not properly shut down (e.g. crashes, reset, bluescreens, etc.). You cannot abort, cancel, delay, or change priority of this operation. Does not occur if system is shut down propery (e.g. Start => Shutdown).

- Does not work on XP-64

- Crude (no support for OCE, RLM or HS)

2. nVidia MediaShield (Onboard RAID)

Advantages:

- O/S independant. Works in XP, 2003, Linux, MacOS, and just about everything else you try to throw at it

- Reads just as fast as XP SRAID, which in turn is about as fast as it gets

- Doesn't need to be rebuilt every time the system crashes

- More resilient to non-failure hardware malfunctions

- Supports online capacity expansion

- Supports RAID level migration

- Supports hot-spare

- Supports hot (un)plugging of entire array(s). Try this with sRAID and good luck getting the array to work again afterwards.

Disadvantages:

- Painfully slow write speeds when small (e.g. Windows' default; 64k) block accesses are used (10-20mB/s)

-- Scales up somewhat with increased block size (50-60mB/s with 1mB blocks)

- Hardware dependant. If the controller fails, you need to get another, nForce-based motherboard.

- Limited to the number of drives supported by your motherboard.

As you can see, neither are particularly enterprise grade, although the nVidia supports many more advanced features than the Windows alternative. nVidia's RAID is also very slow at writing, but both XP sRAID and nVidia RAID is perfectly fast in reads. The choice I suppose depends on your needs - are most accesses going to be reads or writes? What file sizes? Is OCE important to you? etc. As a fileserver, CPU usage may not be important to your needs, however both do use considerable CPU when writing flat out (20-40% on a Sempron 1.6) This is the primary disadvantage of a non-hardware XOR engine.

There is some anecdotal evidence that Linux sRAID is "better", and it is indeed by far the most flexible (if you know how to program, you can pretty much get it to do anything you want), though obviously you'd have to run Linux. It does generally benchmark faster though, but not always by a huge margin.

Edited by qasdfdsaq

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- Very intolerant of intermittent HDD failures (if two drives transiently lose power at the same time, SRAID fails the array with no option for recovery, even if both drives are later reconnected and work fine)

:(

Does it apply to the official windows server raid (I tought server products are supposed to be more solid)?

Is Raid-1 less prone to this issue?

What about Linux raid-5 Sraid in the same situation, is it prone to the same or similar problems?

Edited by jamieshea

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Linux software RAID5 is the best choice.

Why?

IMO if you're serious about RAID besides mirroring, it's best to get a real RAID controller. Not something on a mainboard or in software. Get decent stuff from the likes of IBM and HP if you're going RAID 5 or nested RAID levels. Those controllers are very well supported and usually work in non IBM/HP machines. Usually these are rebranded LSI or Adaptec controllers so those should be fine as well but the nice thing about for example IBM ServeRAID controllers is that you don't necessarily need the exact same controller as a replacement if yours dies. Just get one with the same interface (SAS, SCSI) and compatible firmware/BIOS. The one HP SATA or SAS RAID controller I've used had the exact same software as IBM ServeRAID Manager so I guess what I said for the IBM controllers should be true for the HP's and maybe decent LSI and Adaptec controllers. Really, don't be an amateur with RAID 5. No silly controllers or stuff you can only get on very specific hardware and definitely stay away from Windows RAID 5, even on Server 2k3.

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Does it apply to the official windows server raid (I tought server products are supposed to be more solid)?

Since it's exactly the same, yes, it applies just as much to the server (because it is server RAID in the first place, hacked to work in XP)

Is Raid-1 less prone to this issue?

If you're just using plain RAID1, this issue becomes irrelevant. AFAIK you can't do RAID1+0 or 0+1 in XP anyway.

What about Linux raid-5 Sraid in the same situation, is it prone to the same or similar problems?

I haven't used it extensively, so I can't say. However, it is definately possible to overcome this problem through some fairly simple programming, if it is not incorporated already.

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