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Perc 6/i SSD's Raid 0 Ultra Slow Speed

I have 4 30 GB OCZ Vertex's rated to go around 230 MB/s read. Individually, they go as fast as they should, however on my onboard raid they go super slow in any combination of RAID i try. I found out that the nvidia raid controller on the chipset is not suited for these speeds, so i purchased a Perc 6/i which has been proven to get SSD's at speeds up to 1GB/s. However, even with the perc 6/i using a 128k stripe and a 16k stripe i have not been able to get the 4 SSD's in raid0 to go past 150MB/s, which is much slower than even a single drive. Please help me out! I have no idea why i cant get the speeds these things should be going at! I have updated the Vertex's to the newest firmware, 1.41 which is designed for RAID. Thanks
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WillThomason
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WillThomason
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1 Solution
 
DavidCommented:
What are you using to benchmark it, and what O/S are you using?  Perhaps performance limit is because your O/S and file system are configured to do 4KB I/Os + journaling.

Have you tried raw physical device I/O ?  This takes the file system, file system journaling, and whatever block (allocation size) the file system is configured.

Also you may also just  be better off with software RAID0,  try it and report back what speed.  When you build the file system, be sure to set a block/allocation size to something like 128KB to compare and please report results back

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WillThomasonAuthor Commented:
I am using ATTO and HDTunePro, i am also using Windows 7 ultimate 64bit. I am not sure what my OS and file system are configured to do concerning IO's + jorunaling.

I have not tried a raw physical device I/O, and i dont know how unfortunatly :(

This is my OS drive, is it possible to do software raid on the OS drive?
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DavidCommented:
By the way, are you using the wiper utility before you bench? Wiper is supposed to be run on a daily basis to speed up performance, and certainly before any benchmarking.  It does vital housekeeping.  Best practices for SSDs are also:
 - disable any sort of pre-fetch
 - never never defrag
 - disable drive indexing

RAID controllers rarely work well with SSDs so I really think you will be much better off just letting your O/S build a software RAID0.  Host overhead is not only statistically insignificant, but due to the ability for the O/S to cache I/Os BEFORE sending then to the RAID controller, then you save latency and potentially eliminate need for some I/Os.
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WillThomasonAuthor Commented:
I will use a wiper when this is done formating, i just reinstalled windows 7 on it. I did a format though before each bench, i think that acts as a wiper. Also, can i run software raid on my OS drives? These SSD's will run my windows partition. thanks
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DavidCommented:
Don't do software RAID on the O/S, certainly not RAID0.  Since this is SSD, just use a single disk drive as boot, then create a dynamic disk with 2  of the SSDs, set NTFS allocation to 64KB when you build file system.   Run your bench, then rebuild the array with 3 disks, and try benchmark again.  You should be much better off with either a 2 or 3 disk, but don't know if a 2 or 3-disk RAID0 will be better for you.

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DavidCommented:
format does NOT do a wiper, it actually has the opposite effect, writing a bit to this particular type of SSD makes it take longer to read that same bit UNTIL you run the wipe program.  (There are whitepapers which get into reason in depth)


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DavidCommented:
Found this on care & feeding of your SSD ....

Windows 7

As mentioned above, Windows 7 aligns partitions by default correctly, so there is no need for preparations before installing Win7. Just make sure to delete any partition on the Vertex and create a new one using the Win7 DVD.
Windows operating system tweaks with VERTEX

Before we get started with what tweaks are needed we need to first understand why SSD drives are so fast:
The data seek time on the drive is usually 0.1 to 0.25ms, this means VERTEX will seek out and serve data to your system before a standard spinning platter HDD has even finished seeking.
VERTEX has huge random read and random write performance which is how Windows reads and writes from and to the drive.
So what tweaks do I need to run?
keeping things very simple the following have no need to be enabled on XP.
1 Windows defragmenter
2 prefetch
3 drive indexing

Moving to Vista:
1 Superfetch
2 Windows Defragmenter
3 Drive Indexing

Last Windows 7:
1 Superfetch
2 Windows Defragmenter
3 Drive Indexing

These are the bare minimum you need to turn off, with these off you should see lightening performance from VERTEX, further tweaks can be applied BUT they are more involved and more for those looking to squeeze the extra 3% of performance from their systems.
Windows 7 should by default turn off the following:
Superfetch
Defragger
All you need do now is turn off windows search indexing service and drive indexing.
More on windows tweaks on a new article soon:
Drive maintenance...what can I do to keep it running at full speed?

The simple answer is an application called Wiper.exe. The latest version available to use is 0525 and is linked here for download.
From a fresh brand new drive wiper.exe if run each day will take around 2 minutes max to run and will reset the deleted blocks on the drive to ensure you see full speed. VERTEX works best in IDE mode but AHCI is supported. There are issues with AHCI that need slightly different rules to be applied which i will outline below.
1 Wiper.exe used on a drive in IDE mode will work very fast and is only needed 2 to 3 times per week.
2 Wiper.exe used on a drive in AHCI mode does best when Wiper is run at the start of each new session. If the drive is moving and deleting large amounts of data within a session it may be best to run wiper a few times within that session also. In general at the start of each session should be all that is needed.
Wiper.exe 0525 has proven very safe with both 32bit and 64bit windows OS's, it is a tool supplied to OCZ by Indilinx ( the manufacturer of the SSD controller within the drive) and is free for use by OCZ customers.
What does wiper.exe do?
By default all MLC based SSD drives slow down when each Nand cell has been written to at least once. Even though the data on that cell may have been deleted this means that the controller within the VERTEX has to erase the whole cell before any data can be written to it...this adds latency and so slows the drive down.
Wiper.exe is a brute force method of resetting all those erased cells so that they work at full speed with no added latency..IE they have already been erased.
We have a thread on the SSD forum that shows some good methods for scheduling wiper to run each day or 3 times a week etc...this thread can be found here: http://www.ocztechnologyforum.com/forum/showthread.php?t=57590
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WillThomasonAuthor Commented:
thx for the article, i have those 3 things turned off, and im running ccleaners wipe free space program now. However, wiper.exe does not work with raid so i was unable to use that. I will post results once the wipe free space command completes in a few minutes. Also, i just formated using only 2 SSD's on the perc 6/i incase 4 SSDs was somehow overloading it. Initial results were the same, only 150MB/s but hopefully the wiper will fix that.
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WillThomasonAuthor Commented:
The wiper did not resolve the problem, the speeds are still around 150MB/s and not improving, even with 2 drives. With just 1 drive its 230MB/s. I dont want to split these drives up though or use software raid, i have far to much data that i want to run off this partition and its speed of 4 SSD's in raid0. I have seen several setups where people raid0 their SSD's with the same setup i have, i just havnt figured out what i am doing wrong.
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DavidCommented:
It will only take a few mins, take 2 of the SSDs and configure it for software RAID0, just for benchmarking purposes.  Not all RAID controllers work well with SSDs, some work profoundly poorly, especially with SATA disks.  Perhaps the RAID controller has read cache turned off or NCQ turned off.   But really, I don't see the problem with software RAID0, especially if it works and gives you 400+MB/sec.   Both software RAID0 and hardware RAID0 expose a single physical device to the O/S of the total size of the disks in the RAID set.   RAID0 has no significant additional overhead to the host.   Of course you may not have enough SATA ports on your motherboard, which is reasonable reason to avoid it, but if you have the ports why not try it as a test exercise.  
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WillThomasonAuthor Commented:
software raid0 is when you go into computer management and set them up in raid0 under disk mangemnt correct?
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DavidCommented:
yes.
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WillThomasonAuthor Commented:
After thinking about it some more, software raid0 is not going to help me, and i dont erally want to spend the time trying it now that i am awake again. My goal is to get all 4 SSD's working together with full speed, and i want them to be my OS drive. This is not possible with software raid0. Thanks for your input, but i would really like to solve the problem with the RAID card instead. Thanks for your help though, i do appreciate it, i just dont think its the right solution for my problem.
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DavidCommented:
Bottom line some RAID controllers are not architected for SSDs.  There really is nothing you can do to make the controller faster.  The type of SSD you are choosing requires daily housekeeping to keep it running at optimal speed. It is not possible to maintain your particular choice of SSD (i.e, running wiper) behind a raid controller.

Give up, it just won't work.  Software-based RAID0 is your only option with this type of SSD.
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WillThomasonAuthor Commented:
after fiddeling with the settings some more over and over, i finally settled on some settings that worked, im now seeing 500MB/s read speeds, which is a drastic improvement over the 150mb/s speeds. However, it appears that i cant set my Perc 6/i raid card as the bootable drive when i have the Nvidia chipset raid that has my storage drives enabled. Although in the bios the perc6/i is listed first, it loads the nvidia raid array first and tries to boot. I have to unplug the nvidia drives or disable its raid so it will use the perc 6/i. Any ideas? I am also getting an error message that says "Warning: Have option rom can not be invoke" that happens right before the perc 6/i would load, however this does not happen when i disable the onboard raid.
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MathiauCommented:
I know this is a very very old thread but was wondering what you may have fiddled with?

I have some Dell R610 servers with the PERC 6/i raid cards and i just added 2 Intel DC SD3700 SSD's but they cap out around 100MB's with a single drive and about 230MB/s in a raid 0.

These drives can do 400MB+ on a single drive and the Perc 6/i should be able to do almost a 1Gig of throughput people have reported...
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