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SSD's in RAID 0 + WRITE TO EXISTING HDD- HOW??

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July 9, 2009 7:12:53 PM

Hi Guys,
Ok, so I have bought 2 Samsung 64gb SSD's as an upgrade for my love machine. What I need help with (or preferably pointing in the right direction of some reading) is:

1. Setting up my 2 SSD's in a RAID 0 configuration (I think I know how to do this but tips are appreciated)

2. After doing 1, how do I get them to back up data on my existing HDD (Hitachi 750gb)

I'm reading about this as I wait for them to arrive, so will probably have more questions... :D 

Any help/tips/advice you can divulge will be greatly appreciated.
Thanks in advance

AC

July 10, 2009 7:12:18 AM

This is either a stupid question, a difficult question or this forum is very quiet, I'm not sure which!
There must be someone (looks for sub-mesa and friends :ouch:  )
AC
a c 154 G Storage
July 10, 2009 5:12:21 PM

Patience.....

1) No big deal to build raid-0 with two SSD's. I did it with two X25-M's. In the bios raid manager, they look like any other sata drives. Just link them together as with any other raid-0 setup. I picked a 64k stripe size, but I am not confident that I did good or bad, or if it doesn't matter.

2) Run any backup program you want to copy critical data to your backup drive. Acronis true image can make a clone of the ssd image and restore it later. I would suggest that you do backups to an External drive to eliminate several sources of destruction such a virus, malware, power surge, inadvertent deletion etc...
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July 10, 2009 7:03:40 PM

@geofelt- Thanks for your reply.

1. Ok it sounds relatively simple. I have read (most opinion) that a 128k stripe size is optimal for SSD's but it's not crystal clear.

2. Does the program you mention backup automatically? (I will check when I have a chance just thought I'd ask).

Also, I'm thinking of knocking up a machine to run a home server on, which will obviously help with backing up critical data BUT I have a lot to learn before I am capable of sorting this. Can you point me in the direction of any articles/guides for doing this that you know of? If not I will do it the Google way!

Thanks for your reply. BTW I am patient...sort of.. :D 
Cheers
AC
July 10, 2009 7:13:30 PM

I would use 256KB stripe size if its available or at least 128 and you should notice a decent improvement.
July 10, 2009 7:47:34 PM

just becase it is a SSD doesn't make a raid stripe size optimization change. what matters is the performance of your applications. generally large stripes will benefit read operations while smaller stripes will benefit write operations. you also need to know in what size blocks you should format you drive based on application. e.g. if you are running sql, it writes in 4k chunks. there is a reason why most SAN or DAS arrays will default to 64k stripes. if you are using a MS OS before Vista/server 2008 you have disk alignment issues.

basically, there is no "right or wrong" answer, just the right answer for your situation.
July 10, 2009 8:22:07 PM

spinning rust said:
just becase it is a SSD doesn't make a raid stripe size optimization change. what matters is the performance of your applications. generally large stripes will benefit read operations while smaller stripes will benefit write operations. you also need to know in what size blocks you should format you drive based on application. e.g. if you are running sql, it writes in 4k chunks. there is a reason why most SAN or DAS arrays will default to 64k stripes. if you are using a MS OS before Vista/server 2008 you have disk alignment issues.

basically, there is no "right or wrong" answer, just the right answer for your situation.


Thanks for your replies guys.

@spinning rust- I am running W7 and use my computer for games and surfing in the main. What stripe size would you recommend? How can I find out what size blocks my games use? Is there an industry standard?

Thanks for your help
AC
a c 154 G Storage
July 10, 2009 8:28:31 PM

When researching the stripe size question, I posted the question on several forums. The results from some presumably knowledgeable responders was inconclusive as to any meaningful performance difference. I was looking for real world vs. synthetic differences.
If you can find something definitive, post it here, I want to know.
a c 126 G Storage
July 11, 2009 2:11:22 PM

It depends on the RAID engine. Some stupid RAID engines always read the whole stripe. So if the stripesize is 1MiB, and you want to read 4KB, it would read that 1MiB anyway. That's stupid ofcourse, and the only reason a high stripesize would yield lower results. Because normally, a stripesize can only be too small, not too large.

A stripesize of 1MB or even 10MB would be best for random I/O (either read or write - that does not matter!). The idea behind this is that one I/O request is sent to one physical drive so that the other drives can handle other request simultaniously. This only works is the partition is properly aligned, and not some dumb windows driver at work.

Benchmark in linux/bsd and you will see stripesizes starting from 128KiB yield best random I/O performance. A too low stripesize would cause multiple disks to be working on the same I/O, thus wasting parallel processing potential. If you have a good RAID engine, you should never have to lower the stripesize below 128KiB.
July 13, 2009 6:50:36 PM

Hi,
Ok, so I have my SSD's in a raid 0 configuration, running great, no probs. However, I can't get my storage HDD to work alongside them :pfff:  . It has W7 on it too, could that be the problem? When I boot with the HDD plugged in, I get to the windows logo on bootup and it blue screens (for a fraction of a second) and then reboots.

I have done the repair program (W7 repair option) but no probs found as far as that was concerned. I feel it is possibly a driver problem (now I'm running raid) but I'm not sure what exactly I am basing that on, just a gut feeling!

I have also tried to boot from my HDD but it still crashes. I know the drive is not faulty because I was using it only earlier today (prior to ssd arrival :D  )

So I need your help guys. What should I do to ultimately get my ssd's and my HDD to play nice.
Help greatly appreciated.
AC
!