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SSDs in RAID 0 = Lot of questions

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August 13, 2009 2:40:49 PM

Hi everyone,

I'm currently considering building a new i7 build and I have a few questions about RAID0.

1. I plan to use 2 Intel X25-M 80 GB in RAID 0. I read a lot about data corruption that could happen and RAID 0 being more prone to failing, does it really is that much of a risk? I mean, yeah I have 2 hard drives so I "double" my risk, but honestly, I never had an HDD failing on me (for a desktop) so why would they fail when coupled together? Is the risk really that much higher?

2. I don't have any RAID card at my disposal and was planning on using ICHR10R chipset to do the trick. Does data corruption should preoccupy me?

3. If I go for 3 Crucial SSDs, the combined sequential reads would go over the 625 MB limit of the ICHR10R. What happens then? Does it stutter? Does it corrupt data? Does it fail? Does it just top at 625 MB? Does it affect write operations and if it does, does it cause problem or noticeable slowing on the day to day use?

4. Since RAID 0 will write simultaneously on the 2 or 3 SSDs I will use, the impact on the SSDs life will be big. For every 4k file written, it would have to erase a 128K block before re-writing the whole thing. So basically, for 2 SSD, each drive will have a shorter life of about 50% or a 100% of one of the drives. I read RAID 0 implies a shorter life for the drives and I wanted to know if this happen with SSDs? I mean, yes the whole 128K re-write is a bummer, but is it all? Does RAID 0 apply the same "shorter life" disavantage from HDDs to SSDs as well? Do I misunderstand the whole thing?

Thanks for the help!

John

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a b G Storage
August 14, 2009 8:22:08 AM

1, See 4

2, I suggest you read the RAID FAQ stickied in this section.

3, the 625MB limit simply represents a bottleneck, limiting the full speed of your RAID array. No data corruption should occur.

4, I don't understand how RAID would shorten the life of whatever disks are in the array. The way I see it, you're simply accessing the drives normally. Maybe you'll end up replacing more disks in the long run, but that's only because you're using 3 disks at the same time, instead of the 1-disk-setup that usually characterizes computers.

Hope this helps!
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August 14, 2009 1:01:27 PM

Thanks r_manic for these answers, I was kind of lost here but you shed some light on this.

I read the RAID faq before posting, but that didn't answer my questions.

As I understand your saying...

1 & 4 - There is no more chance of a disk failing in RAID 0 as there is in a single drive configuration. The fact that the 2 SSDs are written simultaneously doesn't impact their reliability only the total life span of the combined drives. If each drive has a 5 years life span then having a RAID 0 setup will wear simultaneously theses drives instead of concurently. That would translate in an (average) 5 years life span for the combined disk under a RAID 0 instead of 10 years for 2 drives under non-raid setup.

2 & 3 - Whenever I top the 625MB/sec limit of the ICH10R chipset I shouldn't have any data corruption, only a slower operation caused by the bottleneck. I assume that would be no badder than waiting for your HDD to get thru, only faster. That means it won't freeze or anything, it will be just slower, just the same as with an HDD. As for the data corruption, I shouldn't worry about it since I have the same reliability as with a non-raid setup minus the bug that might occure in the software RAID, but I guess ICH10R is very reliable and that shouldn't be an issue at all.

I think I got a good idea here, thanks for the answers.
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a c 415 G Storage
August 14, 2009 9:24:19 PM

jonnyberthiaume said:
There is no more chance of a disk failing in RAID 0 as there is in a single drive configuration. The fact that the 2 SSDs are written simultaneously doesn't impact their reliability only the total life span of the combined drives.
Putting a drive in a RAID set won't impact the reliability of THAT DRIVE. But as you noted above the reliability of a 2-volume RAID set is only half the reliability of one of the individual disks alone, because you loose all your data if either drive dies.

The good thing about SSDs is that their normal failure mode is an inability to write new data to the drive. For most SSD failures, you'll still be able to read data from the drive (that's the theory, anyway. Hope I never have to test it! ;) )
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August 14, 2009 9:41:47 PM

1. Do it.

2. Dont stress.

3. Back up the raid array on some other media incase a fail and its easy to rebuild.

4. enjoy your kickass speeds.

5. I have 4 30G in raid 0 and it boots to useable windows in 18sec total. I get 507MB/s reads.
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