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SSD or HDD in RAID configuration and WHY?

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October 19, 2010 7:01:01 PM

Which would you recommend, SSD or regular HDD in RAID configuration and WHY?
a c 99 G Storage
October 20, 2010 6:36:36 PM

SSD all the way. Access times are <0.1ms.

Even with 2 SATA II HDD in RAID 0, and SSD reads can be up to double the RAID array.

A test was done once that did show that 4 x HDD in RAID 0 actually beat a single SSD. It was done with drive striping, so drive use was optimized, but not using the complete drive size (i.e. they partioned the array to only use the first 100GB (?) of each drive, 400GB RAID 0 array, which is the fastest part of a HDD). But, this was done with "older" drives, as the new Seagate 7200.12 and Samsung Spinpoint F3 are faster now.

Still, my RAID 0 arrays showed my SSD array at reads over 300MBps, and my HDD array peaking at 150MBps. (BTW: I only RAID'd my SSD due to their size, I don't recommend thii to a newbie.)

I just picked up an OCZ Agility 2 60GB SATA II SSD for $139.99, with a $20.00 rebate coming. This is only a little more than 2 x HHD at 1TB+. This drive has the new SandForce 1200 controller, with read/writes around 285/250MBps.

You loose size, but gain speed!

BUT, write speeds can be less with a SSD. But once the OS is installed, reads are were it at!
a b G Storage
October 20, 2010 7:28:07 PM

Another differnce is Windows load speed. SSD's excel when it comes to loading small files. My pair of 7200.12s have excellent read speeds Max 140MB single or MAX 250MB+ RAID 0 but will never load windows as fast as an SSD.

So 2x 500GB 7200.12 are also 20% cheaper than a 60GB SSD.
For Large files, HDDs are much better value, but for loading lots of small files SSDs rock.

Related resources
a c 99 G Storage
October 21, 2010 3:09:50 AM

^ Agree!
a b G Storage
October 21, 2010 3:41:28 AM

1. The random 4K read/write for SSDs can't be beaten by a HDD. Period. Even the 15k rpm SAS drives don't come close.

2. The entire system is more responsive with an SSD.

3. You do trade speed for size.

4. Unless you have an Intel board I would not recommend RAID as you will loose TRIM support with out the Intel RST on RAID. You can use the Microsoft AHCI drivers but this will be slower.

5. If you are just using this as mainly storage, get HDDs, if it's for the OS, just get a single SSD drive. A 120GB Vertex 2 is ~$250.
October 27, 2010 3:34:24 AM

Plumble said:
Another differnce is Windows load speed. SSD's excel when it comes to loading small files. My pair of 7200.12s have excellent read speeds Max 140MB single or MAX 250MB+ RAID 0 but will never load windows as fast as an SSD.

So 2x 500GB 7200.12 are also 20% cheaper than a 60GB SSD.
For Large files, HDDs are much better value, but for loading lots of small files SSDs rock.

Very true.
But, how 'bout two 64gb SSD's in RAID0 for your OS and main programs with 2 250 gb hdd's in RAID0 and a 500 gb hdd to back them up for storage?
Overtime anyone?
a b G Storage
October 27, 2010 4:27:42 AM

^ NEVER run RAID0 on a backup/data storage drive.
a b G Storage
October 27, 2010 6:51:14 AM

In short HDD is still the best choice. cheaper and reliable.
a b G Storage
October 27, 2010 3:37:53 PM

^ Cheaper, yes, reliable? That's debatable. Btw, when I said not to run RAID0 I meant that for data/storage drives since if the array fails or one of the HDDs die, your data is history. This will be the case for both HDDs and SSDs in RAID 0.
a b G Storage
October 27, 2010 6:31:30 PM

Don't forget that SSDs have a shorter lifetim (last I heard).
Ther performance of two SSDs in RAID 0 is very good indeed, but to back up the OS you would need to put a mirror (RAID 1) witch will run at the speed of the slowest drive.

Please remember that the disk speed is far from the limiting factor in performance PCs. You get far better value upgrading the CPU or GPU.
a b G Storage
October 27, 2010 10:29:18 PM

^ In most of the modern systems (esp. i7/X6 with 5870s,etc) the limitation is the HDD. The lack luster performance of HDDs in random IO is a problem for an OS drive. I'm not saying you should just go out and buy a SSD today, but I and many others (Anand,et al ) agree that for a good mid high and up system, an SSD is one of the best upgrades to make.

As for SSD reliability this is only a problem in a server type environment where the SSD load is much higher, this is why most Enterprise SSDs use SLC and not MLC. For consumer SSDs, the Flash chips should last at least 3-5 years or more. Anand or some one else actually calculated the life of an SSD I'll see if I can find it.

edit:
Found one, not the exact one I was talking about, but it will do: http://www.storagesearch.com/ssdmyths-endurance.html
Quote:
To get that very high speed the process will have to write big blocks (which also simplifies the calculation).

We assume perfect wear leveling which means we need to fill the disk 2 million times to get to the write endurance limit.

2 million (write endurance) x 64G (capacity) divided by 80M bytes / sec gives the endurance limited life in seconds.

That's a meaningless number - which needs to be divided by seconds in an hour, hours in a day etc etc to give...

The end result is 51 years!

Obviously, 51 years is assuming a perfect wear leveling, but it will last at least 5 years for any modern SSD.

Also for Flash drives, you can write quite a lot of data before the drive becomes read only. A modern SSD/Flash will not just "stop" working when they reach their life. Your data will not "disappear". You will still be able to read the data, however you will not be able to write anything.
a b G Storage
October 28, 2010 8:57:52 AM

Shadow703793 said:
^ In most of the modern systems (esp. i7/X6 with 5870s,etc) the limitation is the HDD. The lack luster performance of HDDs in random IO is a problem for an OS drive. I'm not saying you should just go out and buy a SSD today, but I and many others (Anand,et al ) agree that for a good mid high and up system, an SSD is one of the best upgrades to make.

[/b]

I stand corrected.

dxb, what are your system specs?
!