RAID 5 Questions

tombowler

tombowler

tombowler

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Joined
22 Aug 2011
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4
Hey, I've just brought 3x 2Tb Samsung Spinpoint F4's ...
I've set them up using the motherboards onboard raid system (MSI P67A-GD53)

And I've started to transfer my data over (several terrabytes of it)
For the first part it seemed to be going well, the stuff transferred at about 30-35 MB/s

However now I'm getting about 7 MB/s ...
Also if I try and navigate through the drive during the copying the whole thing seems to lag up terribly.

So, my questions (appologies if they're self explanatory / simple)
1) Can I add extra drives to the RAID 5 array without losing all my data / having to back it up and rebuild

2) Is the fact my raid is beginning to get quite full the cause of it to slow down horribly ... Of the 4Tb of space I have about 1.1 Tb left

3) How will I know if one of my drives is failing / failed, as I've heard this can cause a significant loss in performance (Hopefully not this ... since the drives are only 3 days old)

4) Is there any way to skip the RAID config screen during boot - Since I've set the RAID up ... I don't really need to access that again

5) I'll edit this one later ... I can't remember waht it was now...


Thanks for any replies. Help is appreciated :)
 
I wanted some redundancy ... with the smallest expense.
The 4tb capacity I have at the moment is running out, so in order to expand as you suggest, I'd need to buy another 3 hard drives :( .... £150
 
Redundancy is different from backups (although you may have adequete backups already, in which case you don't need to buy any drives.) . Theres's also more than just hard drives to think about in terms of redundancy, do you have a redundant controller or backup motherboard with the same raid controller? Other wise a blown board or a power surge could lose your data for good.

How 'expensive' is the data? Is it worth the extra money on hard drives? Redundancy will only get you uptime.

Well if your 4TB runs out you'll need to buy more drives anyway? Without raid you can just wap it in and go. With RAID you have to futz about adding a disk and rebuilding the array, possibly breaking it in the process.
 
Do not run RAID-5 from the onboard chipset. RAID-5 should only be run off a dedicated RAID controller with onboard RAM.

The issue with performance is via the motherboard controller. Although it supports RAID-5 it is not really geared up for it. I'm not sure but I think the CRC partity data is generated from software which explains the performance loss.

I found that a good way of doing redundancy is by having an OS drive (I have an SSD but any 7,200rpm drive is ok). Then have an extra two HDDs not in RAID but standalone. The reason is that if you want redundancy in RAID you only have 1 or 5. Explained 5 is not a good idea but using 1 means double the cost for half the space. If you run the drives in standalone you can have a mirror of all your important data and use the extra space for whatever you want. It's also usefull for say extracting a RAR or demuxing video as you can use one drive for read and the second for write so it makes the process much quicker.
 
Buy another HD and run them in RAID 10, I use SSD + RAID 10 on my home PC. Had a HD fail in the array a few weeks back, just swapped it for a new one and it was good to go.
 
Thanks for the replies, I would have done it differently now. But alas thats the way I've done it. I just looked, and my motherboard doesn't actually support any more SATA ports ... so adding an extra drive can't be done :(

Does anyone know the answers to the questions in my original post? - Namely the sudden slow down, as I've heard a drive failure does it .. and now I'm concerned
 
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