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I am buying a new Dell T-7500 workstation. My application is stock market trading.

After a Hard Disk crash once, I learned that I need an extra hard disk always ready in case one fails.

Dell is offerring either software based Raid -1 OR Hardware based Raid-5 on this system.

Specs of system are :

CPU : Intel Xeon E 5645 at 2.4 Ghz

8 GB ECC DDR3 RAM

500 GB SATA 7200 RPM HDD

Windows - 7 Ultimate 64 bit

Currently I clone my HDD every night using Acronis True Image Home so that I always have an Identical HDD ready.

Even if I get a Raid system I still would like to continue clonning a HDD every night & keep them in a remote locations.

I am not much of a technical person so if anything goes wrong I will need Dell's help.

Please I need advice.

Thank You.

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migrated from serverfault.com Jan 19 '12 at 14:47

This question came from our site for professional system and network administrators.

    
it's more suitable for superuser; regardless of raid choice - think about getting raid-suitable disks [ eg WD RE4 ]. –  pQd Jan 19 '12 at 12:15
    
Thank you all for such an overwhleming response. Yes, I am a Daytrader. Let me explain what I am trying to achieve. I basically want an exact copy of the current drive ready all the time in case the current one fails which I can basically either plug in or have already plugged in. I dont want to mess around drive image restoring, restoring from back ups, trying to find what data am I missing when primary drive fails that I can replace from my backups etc etc. If primary drive fails all that I want to do is replace it with a clone drive in few minures & ready to go. Why is it so difficult in th –  user114743 Jan 22 '12 at 2:13
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4 Answers

Not a software person, but you're a day trader?

Given those options, here's how I boil it down.

FAKE RAID - RAID on the motherboard - I avoid it like the plague.

Software RAID - Good enough for home users most of the time. Performance is fine. Works. But you do need more expertise in that you need to find a way to know which drive has failed when there's a problem. "Drive error" doesn't mean you'll know which in the chassis needs replacement, and for a non-tech person this can be frustrating; you'll need in-home support.

Hardware RAID - Safer (as the controller can cache data and has on-board memory/battery support) and often/usually has a way of notifying you which drive has failed. If you have proper disk support, when the drive fails you can pull it out and swap a new one in without even powering down the computer. Expensive, very expensive, compared to software RAID. But having a nice blinky light to say THIS DRIVE HERE FAILED! and the convenience of hot-swap is very nice, especially for cutting down on hassle and is much easier in the long run. You'll want swappable drive bays to support the hot-swap feature. Nearly invisible to the OS, too, so you don't usually have to worry so much about driver support; you create the volume using the controller's tools at boot time, then install the OS to the drive volume.

So, if you have the $$ to burn and absolutely want the least headache, go hardware. If you want good enough and save some cash, go software in the OS. If you're thinking of using motherboard fake raid, change your mind.

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IMHO software raid from on board (OS level) is good enough for that. If anything fails the worst thing happening is a manual boot into the second boot entry in the windows boot loader.

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Although I'm automatically anti Software RAID, I agree with this given those options. You won't want to be faffing with RAID rebuilds etc, so I doubt RAID 5 will give you any benefits. –  Dan Jan 19 '12 at 11:35
    
I am with you contra aid OTUSIDE A simple mirror for the workstation. I love my adaptecs. There also is a risk of the bios not booting the sdecond disc automatically. All this is irre,klevant fora boot system mirror ;) Here also cost counts. Raid 5 will make the slow discs even much slower. –  TomTom Jan 19 '12 at 11:38
    
If we are using a RAID controller as described in say RAID1, in the event of the primary drive going down, I doubt selecting anything in Windows boot loader will help as the two drives are presented to the PC as one through the controller. Also the risk of it not booting from the second disc is real, and for a boot system mirror it is very relevant as the PC may no longer boot. –  Robin Gill Jan 19 '12 at 12:51
    
Yes, but that is lost money ;) I had tons of peoroblems with cheap on board raid and no problem (ever) with windows raid fpr boot. You may have to selec anotehr syste mfor boot but hey - you are in front of the machine. this is a real issue for a server, zero for a workstation. –  TomTom Jan 19 '12 at 12:58
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I would go for the software RAID-1 option if I were you (if only because it's RAID1 instead of RAID5). RAID1 is two hard drives with one operating as an exact mirror of the other one; if one of your hard drives dies, then you can continue operating as normal on the second one.

In your case if a hard drive were to die in this situation you could just replace it with a new one the next day and continue operating with two drives again without having to worry about any down time as the array rebuilds etc (as will occur with RAID5). This keeps your spare cloned hard-drive untouched until it's really needed one day and protected on the off chance that your second hard drive dies while rebuilding the array on the new disk.

The software versus hardware debate for you is largely irrelevant, in my opinion, and RAID1 / RAID5 is the more pertinent issue.

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I'm assuming by software RAID you are talking about what are commonly referred to as fake RAID controllers - i.e. RAID controllers that offload their work to the CPU as they don't have neccessary intelligence to do so on the card.

I have no trust in software/fake RAID, I've seen a dell precision 390 with raid 1 killed by a power outage. When I got the PC back to base in the end all I actually needed to do was disconnect the primary drive and it booted fine from the 2nd.

I also remember some fun and games with a Poweredge SC1425 (CERC/fake raid) - pair of brand new hitachi enterprise class SATA drives but one had a bad sector, after I had loaded on a certain amount of software the server would continually bluescreen when starting up.

Also remember a Poweredge T105 with a PERC S??? (again fake raid), one drive developed a few bad sectors while in production, the server was taking around 2 hours to boot up and was practically unusable.

Basically with software RAID, in the event of a problem, you should hopefully have a good set of your data on one drive, but don't count on actually being able to do much with it without some kind of intervention.

With a decent hardware RAID controller, rather than continually retrying, if it finds a bad drive it will knock it offline and carry on using the other one.

Myself at home, I'm using a Precision T7400 with a PERC 5/i - the only downside is that it takes a little longer to boot as the RAID BIOS has to do it's thing after the main BIOS, however it's a lot faster than the onboard SAS 6/iR, and also I have the battery backed cache unit, so any data that has been sent to the controller/drives will be battery backed for 72 hours in the case of a power failure before the data gets written, and this then gets written to the drive when the box is next turned on.

The only snag with using a Dell hardware controller is that sometimes they can have moods when using drives not supplied/certified by Dell which happen to be well over the going rate.

I agree with the comments about RAID 1 rather than RAID 5, I'm pretty certain the hardware RAID should support RAID 1 as well, but it may be an idea to check first.

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