MB Raid or Raid card? pls help

daz87uk

daz87uk

daz87uk

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Im thinking about getting a new system, and for it I wanted 4x 1TB WD Blacks
in raid. I was told the other day that raid cards perform better than the raid built onto MB. So is this true and what differences will i see? is it worth the cash. also im not sure what raid to use maybe 5 but ive never done it before so im clueless:confused:. anyhelp would be much appreciated
 
What motherboard have you got? What type of raid did you want to run?

If you arn't planning to run a demanding RAID level, and have a fairly modern board, MB RAID is fine.
If you want to run RAID 5, go hardware.
Bear in mind a proper hardware RAID card costs >200 quid new.
 
I havnt got the system yet, I was just getting the plans in my head before I brought the gear if you know what i mean. I would like the new Gigabyte GA-MA790FXT-UD5P (Socket AM3). 4 of the WD blacks to use as my main operating and storage, as I have a lot of stuff and I dont want to loose it.
I wanted the max speed out of the raid and reliability most of all, I had a look at some charts that seemed to say raid 5 was ok. but i really havnt a clue, what raid to choose... fast and reliable thats all i want really if it required a cheaper add on card i would get that but not £200 thats far to pricey. thanks for your reply
 
o for the type i want all 4 harddisk to act as one and backup would be a quarter for each drive so i loose 1TB for backup. in theory giving me 300mb/s and reliability.
but thats all i know about raid i still dont know what one to choose
 
I went for a card since if I upgrade my motherboard at any time I can take the RAID with me, and also dedicated cards normally have better performance

Stelly
 
sounds like what you want is RAID 0+1 - has the write speed of two drives in RAID 0, the read speed of 4 drives in RAID 0 (I think), and each drive has a backup in case of failure. But if you're really worried about losing the data you should have external backups with separate power supplies that aren't plugged in most of the time.
 
Cheers for your help, raid if anything is a lot safer than just the single 1Tb I got now. I think I'll go for that option more than the external backups because i want the combined speed as well plus it would be cheaper not to caddy them :). the card idea sounds good as well for memory reasons. but I dont upgrade that often so im not sure if it would be worth it. ive had this pc now for almost 4 years. Its still fast and can play all the new games so if I get this it will prob be another 4 or 5 years before I need to consider upgrading again. well I think raid 0-1 cards are the cheap cards anyway, decisions are hard lol. :D
 
Hmmm, i'm not sure you have the raid levels correct, the suggestion above (0+1) would loose you 2TB of drive space.

To only loose 1 drive and still have some form of recoverability if 1 fails you would need to use Raid 5 (there are others that are very similar but 5 is the common one). This may not be so hot on a motherboard controller.

I'll do a quick n dirty guide to raid levels:

Raid0: Striping, no resiliance, 2 or more drives striped for speed (saves half the data to each drive so improves performance, drives used in parallel during read/write). If ANY drive dies your data is toast.
Raid1: Mirrior. Usually 2 drives, you loose 1 drives space as it basically just makes 2 copies of your data.
Raid5: Striping with Parity 3 drives+. You loose 1 drive's worth of space for parity but this setup has the speed of striping with the ability to suffer a single drive failure without data loss. Raid 5 generally needs a hardware controller tho as the parity calculations slow things down.

With your motherboard controller it's doing raid 5 in software. The system processor gets handed the calculations to do. Speed wise it varies so try and find a review.
 
Mercutio said:
Hmmm, i'm not sure you have the raid levels correct, the suggestion above (0+1) would loose you 2TB of drive space.

To only loose 1 drive and still have some form of recoverability if 1 fails you would need to use Raid 5 (there are others that are very similar but 5 is the common one). This may not be so hot on a motherboard controller.

I'll do a quick n dirty guide to raid levels:

Raid0: Striping, no resiliance, 2 or more drives striped for speed (saves half the data to each drive so improves performance, drives used in parallel during read/write). If ANY drive dies your data is toast.
Raid1: Mirrior. Usually 2 drives, you loose 1 drives space as it basically just makes 2 copies of your data.
Raid5: Striping with Parity 3 drives+. You loose 1 drive's worth of space for parity but this setup has the speed of striping with the ability to suffer a single drive failure without data loss. Raid 5 generally needs a hardware controller tho as the parity calculations slow things down.

With your motherboard controller it's doing raid 5 in software. The system processor gets handed the calculations to do. Speed wise it varies so try and find a review.
Click to expand...

I think I remember reading that with 1TB drives RAID 5 is no longer recommended as the statistical chances of another drive failing during the rebuild is too high (especially with consumer level hard drives). If that happens the entire array is toast.

RAID 6 is OK for now, but once we start seeing 2TB disks that too will start looking ropey.
 
Mercutio said:
Hmmm, i'm not sure you have the raid levels correct, the suggestion above (0+1) would loose you 2TB of drive space.

To only loose 1 drive and still have some form of recoverability if 1 fails you would need to use Raid 5 (there are others that are very similar but 5 is the common one). This may not be so hot on a motherboard controller.

I'll do a quick n dirty guide to raid levels:

Raid0: Striping, no resiliance, 2 or more drives striped for speed (saves half the data to each drive so improves performance, drives used in parallel during read/write). If ANY drive dies your data is toast.
Raid1: Mirrior. Usually 2 drives, you loose 1 drives space as it basically just makes 2 copies of your data.
Raid5: Striping with Parity 3 drives+. You loose 1 drive's worth of space for parity but this setup has the speed of striping with the ability to suffer a single drive failure without data loss. Raid 5 generally needs a hardware controller tho as the parity calculations slow things down.

With your motherboard controller it's doing raid 5 in software. The system processor gets handed the calculations to do. Speed wise it varies so try and find a review.
Click to expand...

Anyhow, unless I've got my facts badly wrong, RAID 0+1 is RAID 0ing two of the drives, and mirroring them. This leaves 2TB space (out of 4TB, but he wants reliable storage), the same amount of disk space left using RAID 5. (Note: there are 4 1TB drives; for RAID 5 to work, each drive would have to be 50% dedicated to storing 166GB from each of the other three drives, 3x166=500ish) and 50% of its own storage).

philjohn said:
I think I remember reading that with 1TB drives RAID 5 is no longer recommended as the statistical chances of another drive failing during the rebuild is too high (especially with consumer level hard drives). If that happens the entire array is toast.

RAID 6 is OK for now, but once we start seeing 2TB disks that too will start looking ropey.
Click to expand...

I recall reading that too. I think the major flaw I saw with the article was that it was based on the premise that if one drive failed, the drives in the rest of the array would have to read all their data to rebuild the array, which is bunkum - they would only have to read the data pertaining to the disk that had failed. So with the unreadable bit error (which would happen once in every 8TB or something was it?), large arrays are affected no more than small arrays - it is the size of the hard disks that make it up that count.
So yes, it'll start being more common with larger disk sizes but RAID 5 is hardly as redundant as the article made out.

(If I've made some mistake here with my calculations/deductions, feel free to correct me, hard drive statistics is hardly a specialty of mine :p)
 
Thanks;) so Raid 5. thats gonna hurt the wallet with the prices of raid 5 cards. just hope prices come down a little more bofore i get this underway. :cool:
 
RAID 0+1 has striping and recoverability; RAID 5 just has recoverability. So RAID 0+1 is faster than RAID 5, more reliable than RAID 0/no RAID (although in the low chance of an unreadable bit when recovering a disk, less reliable than RAID 5), so combined with cheaper controller prices (if they can do RAID0+1 not just RAID 0 or 1), IMHO RAID0+1 makes much better sense than RAID 5.
 
Daz, bear in mind that for the price of a proper RAID5 card, you could just buy the extra drives needed for a RAID 10 / 01.
Mini - RAID5 is faster than a RAID 10/01 setup with the same number of disks. It stripes the data as well as doing parity calcs. RAID 5 is the same speed as a RAID 0 array with one less disk. RAID 10/01 is the same speed as a RAID0 array with half the number of disks.
 
Last edited:
Zarf said:
Daz, bear in mind that for the price of a proper RAID5 card, you could just buy the extra drives needed for a RAID 10 / 01.
Mini - RAID5 is faster than a RAID 10/01 setup with the same number of disks. It stripes the data as well as doing parity calcs. RAID 5 is the same speed as a RAID 0 array with one less disk. RAID 10/01 is the same speed as a RAID0 array with half the number of disks.
Click to expand...

Ah ok, I didn't realise RAID 5 data was striped. So RAID 5 is faster than RAID 01 then.

Thanks for clearing that up.

But extra drives needed for RAID 01? In both RAID 5 and RAID 01, only half the total data capacity of the drives is available, so unless I'm missing something, the OP would have 2TB available of his 4TB either way?
 
miniyazz said:
Ah ok, I didn't realise RAID 5 data was striped. So RAID 5 is faster than RAID 01 then.

Thanks for clearing that up.

But extra drives needed for RAID 01? In both RAID 5 and RAID 01, only half the total data capacity of the drives is available, so unless I'm missing something, the OP would have 2TB available of his 4TB either way?
Click to expand...

The beauty of RAID5 is that you only lose one disk's worth of space to the parity calcs, so in an array of 4 drives you'd get 3 drives worth of usable space, and sequential speeds would be roughly the same as a 3 drive raid 0 stripe.
Of course, doing the parity calcs requires you to have a decent RAID controller, or your write speeds suffer.
 
Zarf said:
Of course, doing the parity calcs requires you to have a decent RAID controller, or your write speeds suffer.
Click to expand...
Parity calculations aren't the problem but the fact that RAID5 write often requires reading from one or more of the drives before parity data can be calculated. And that's painfully slow with HDDs.
Pretty much only way for preventing this bottleneck from showing badly is use of big write cache.

SSDs might actually change this because they have much faster access speed... but until that RAID10 is the RAID mode which gives the most consistent performance.
 
bad point over raid 10 from the listed site


Disadvantages
Not a "True" RAID because it is NOT fault-tolerant

The failure of just one drive will result in all data in an array being lost

Should never be used in mission critical environments
 
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