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New Raid 5 Very Slow

Posted on 2010-11-17
Medium Priority
Last Modified: 2016-06-26
I just created a new RAID 5 array on my Vista 64 computer using 3x 1 TB Western Digital Caviar Blacks Model# WD1001FALS.

It seems to be much slower than I had hoped, I get random momentary freezes also but then the computer will come back.

Here is a link to my computers specs. The Raid is on the Motherboard. System Specs here

I have attached some HD Tune Screenshots. One image is of 1 Single HD with decent speeds.
The next 3 are screen shots of the Raid 5. You can see there is a very wide range of results. During this time of all 3 I only have open firefox and am not doing any major tasks or strains.

 1HD-11-14-10.png Raid5-3HD-11-17-10a.png Raid5-3HD-11-17-10b.png Raid5-3HD-11-17-10c.png Raid5-3HD-11-17-10d.png
Question by:shawnzer
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LVL 47

Accepted Solution

David earned 668 total points
ID: 34160792
Your performance and the locking up is to be expected.  You have a "fakeraid" controller.  The work is being done by a device driver.

If you want better performance, turn it off, and let Vista do software-based RAID1.  This will utilize load balancing so you will get better performance on reads then on a single disk (providing your workload is balanced), and writes will also be about twice as fast as what you are getting with the RAID5 fakeraid.

Your disks are also not qualified for use behind a raid controller, so that could explain some of the stability issues.
LVL 11

Assisted Solution

louisreeves earned 668 total points
ID: 34161026
Graphical anaylysis notwithstanding, There are many reasons Solid State is not widley accepted  (or Wise)at the enterprise level.  If you have enough money, you can get anything to work. That said, I am presenting the argument to you as I understand it. (Before starting, I am wondering what kind of controller this has) If it is software raid, I wont post on the issue again, as the issue should be obvios at that point. In terms of an enterprise level hardware setup, applying a solid state raid 5 has issues that are best descibed as diminishing returns for attaining "performance". I looked really hard for the article I found on the matter for you and could not find it. I will attach it if I do find it. Stated simply- It is very Novel to use the system start right up. - Beyond that - Go get a SAN or buy a Regular PERC 6 and disk array.

The basic test was run in a larrge  production environment and the Slow Write speed alone made the raid 5 completely inferior for enterprise usage.  I can sum this up as follows:

1. Solid State has an inherent write speed weakness
2,. Hard drive prices continue to fall and space continues to increase
3. Failures in hard drives continues to fall
4. Solid state has durability issues compared to disk
5. Enterprise storage is moving toward Central SAN storage.

This was the jist of what I read:




A silid State raid 5 is not enterprise proven. Because of this I would talk to the hardware vendor and look at the design specks for the drive firmware and driver, and raid controller driver and firmware. Are they designed for raid 5? what are the benchmarks?

LVL 47

Expert Comment

ID: 34161195
Well, the Caviar drives are also not appropriate for a raid controller, either, as I stated previously.  YOu might want to read this document that gets into some reasons.  

The PERC6 controller, or for that matter, any of the ones using the LSI 38xx or 2x08 controllers MUST use enterprise-class SATA (or SAS disks).  LSI, Dell, HP, IBM, Intel, and i expect the other manufacturers that OEM boards made on this chipset simply do not qualify desktop class HDDs.  Due to the TLER issue, they are not suitable.


Author Comment

ID: 34163649
So is any raid going to be reliable with my MB if I switched to raid drives?

Or only if I get a raid controller
LVL 47

Expert Comment

ID: 34163672
The RAID drives will make it more reliable no matter what MB you use.  Read the specs on the disks!

Assisted Solution

driskollt earned 664 total points
ID: 34176249
Instead of spending lots of cash...
You could...
Spend $200 on a 120 OCZ Vertex SSD for your OS/App volume (still going to be better bang for your buck than a bunch of SATAN drives behind ghetto RAID).

Keep the RAID-5 for your archive/media storage - or drop a drive (or get another) and use RAID10 with your onboard RAID controller.

Your consumer-level RAID is going to pretty much suck.  You aren't getting read/write cache or intelligent write cache/prefecthing algorithms.  I personally would probably never use RAID-5 without a proper RAID controller.

Also, MB/s is not a good way to measure hard drive performance - IOPS is always the best way.  Any drive can look super fast in MB/s when you use the perfect IO size and sequential.  IOPS is what matters.  And 77 IOPS is about what a single SATAN drive can sustain.


Expert Comment

ID: 34176254
And yes - I said SATAN on purpose :)

Author Comment

ID: 34210325
well what would be better RAID 10 or 1 SSD for the OS then keep a Raid  1 for Redundancy
LVL 47

Expert Comment

ID: 34210541
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