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Looking at the OCZ SSD's for a Web Server, any opinions

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April 28, 2010 3:14:57 PM

I have two different servers that will be equipped with SSD's.

The first is only to run Windows Web Server 2008 and IIS 7.0. Any recommendations, don't need huge disks, but am looking at running 5 of them in a Raid 5. Looking at OCZ's and Intels.

The second server is for running SQL Server 2008 on Windows 7 Ultimate 64. Any advice of do's and don'ts for SSD's with running SQL Server 2008.
a c 127 G Storage
April 28, 2010 4:00:33 PM

Do:
- pick Intel SSDs; they are great. You would need about 10 OCZ SSDs to match the speed of a single Intel regarding random write
- align them properly and test alignment with AS SSD utility (downloadable via google)
- use a good controller for RAID5; or software RAID for RAID0
- use a Battery Backup Unit (BBU) if you're going to use RAID5

Don't
- pick SSDs with low random write
- defragment them
- use all available space; since you are running RAID5 you NEED to reserve space on the SSD; i.e. if the SSD is 80GB you should create a 40GB partition and not use the other 40GB.

Also be aware that even a single SSD can bottleneck an expensive Areca-class Hardware RAID controller; as these are typically limited to 70.000 IOps. A RAID of Intel SSDs will go beyond that; so consider yourself 'capped' to 70k IOps.

Also; alignment with RAID5 is a bit tricky. Assuming 1024K offset (Vista/Win7) you would need an uneven number of disks; so 5 SSDs for example; with 128KiB stripesize that would get you a full stripe block of (5-1) * 128KiB = 512KiB which is fine with 1024K offset. However, if you pick 4 SSDs in RAID5 that would be (4-1) * 128KiB = 384KiB which is not aligned with 1024K - lower performance and less endurance is the result. Generally, RAID5 and SSDs is not an ideal combination.
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April 28, 2010 4:44:43 PM

Thanks for the reply.

I am using an Intel S5520HCR motherboard (ICH10R) (along with an Intel x5600 CPU). Was that an ok purchase. I am sacrificing some performance over RAID add-ins, but I would assume that this wil be ok? Right?

I am not sure what you mean by "align them properly". I have 4 SSD's in my development system that are in a RAID 0 and using Win 7 Ultimate and a Gigabyte (UD5) motherboard with the ICH10R controller, the installation was seamless. Did I do something wrong in letting Windows 7 handle everthing for me?

Am I even getting the benefit of RAID 0 on my development system with the 4 SSD's or was it a waste?

It is hard to tell by the specs of OCZ vs Intel that the Intel is better. What do I need to look for to be able to see that?

By battery backup, do you mean a UPS for the system, or something that I added internally just for the SSD's?

What is the reason to give up half (40GB) of drive space on the RAID 5, and would I be better off using a RAID 10?

Thanks



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a c 127 G Storage
April 28, 2010 4:50:19 PM

About alignment; easiest is just to run AS SSD and you will instantly if it aligned or not. Alignment is different/more complicated when using RAID5 or RAID6.

Quote:
It is hard to tell by the specs of OCZ vs Intel that the Intel is better. What do I need to look for to be able to see that?

Random read/write; that is why you buy an SSD anyway not because throughput is twice that of HDDs; if that was all the difference nobody would buy SSDs.

Quote:
By battery backup, do you mean a UPS for the system, or something that I added internally just for the SSD's?

BBU = battery for hardware RAID controller. I am assuming you won't be doing RAID5 with onboard RAID?

Quote:
What is the reason to give up half (40GB) of drive space

Because you lack TRIM support when using SSDs in RAID. Without TRIM; SSDs will slow down if you don't take precautions. You would need to reserve space to keep the SSDs fast over time.
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a b G Storage
May 2, 2010 9:57:10 PM

Well said Sub mesa.

If you plan to do RAID 5, I highly recommend you get a quality (true) hardware based RAID card. Like sub said, these are becoming a bottle neck with SSDs; I expect manufactures to ship RAID cards aimed at SSDs by end of this year.

I would also recommend an Intel SSD for the simple fact that they have been in the market for a while and haven't had any major issues.

You may also want to consider a RAM drive depending on the size of the website,files,etc you are hosting. Assuming you have enough RAM and the files/website is small, it is quite possible to do this.
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May 10, 2010 12:57:12 PM

Since I would have to give up so much disk space with the SSD's because of no Trim support in a RAID 0 configuration, I am thinking about forgetting about the striping array and just mirroring them instead. I assume that that would be ok, right? Nothing trick about that?

And since the Intel SSD's are so fast, am I going to really notice the difference that much anyway?
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a c 127 G Storage
May 10, 2010 1:50:13 PM

SSDs in RAID, even in a mirror, will not be able to use TRIM. Perhaps if you use software RAID in Windows itself, but it won't be bootable.
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May 10, 2010 1:54:19 PM

So, really my only choice is no raid, or to partition the drives so that half of the disk is only used, correct? What happens to the rest of the disk since it isn't partitioned. Are Raided SSD's a bad idea in general?
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a c 127 G Storage
May 10, 2010 1:59:42 PM

I'm using four Intel X25-V 40GB in RAID0; i don't think its a bad idea. But it comes at a price; you can only use part of the capacity if you want to keep them tidy and fast.

TRIM with SSDs in RAID only works on Linux and BSD at the moment; Windows users cannot have TRIM at all if not using the Microsoft AHCI/IDE driver or the Intel AHCI/RAID driver. Only those two drivers passthrough the TRIM command to SSDs not in a RAID.

The 'unused' parts are actually used by the SSD internally to 'remap' small writes. For that to work it needs free blocks; either TRIM would make sure the SSD has enough free blocks; or by reserving a large part of the SSD you guarantee this portion to be available to the SSD internally.
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May 10, 2010 3:34:49 PM

Thanks very much for your help!

A few more questions...

Since this server is just a Web App Server running Windows Web Server 2008 R2, which is where the majority of the processing will take place, I will probaby run a striping array, no mirroring since the data is on a different drive and the Web App is always backed up and doesn't need the real time access. Also, it really does not need a tremendous amount of space since it will basically be running Windows Web Server 2008 R2 on it, and the Web Apps themselves will not be huge so my investment in the fast Intel SSD's wont' be huge.

I will be using the Intel S5520HCR motherboard with the new Xeon X5650 processor. The S5520HCR has the built-in ICH10R controller, and I would like to use it. It looks like it uses the native PCI Express architecture and high-speed cache (http://www.intel.com/products/server/raid/index.htm) that I believe is usually the difference in using an add-on card. I know that you don't recommend the built-in RAID, but I don't mind sacrificing some performance for the convenience. What would the difference in performance be? What would my cap for IOPS with it be vs. an add-on controller such as the.

For RAID 5, Intel offers this "SATA RAID 5 Activation Key" that is a software key. I assume it is just to make RAID 5 active, but is there anything special about it whereby it does the software TRIM you had mentioned earlier. Does the new Intel RAID solve any of the TRIM problems for SSD's. Looking at the Intel webstie, (http://www.intel.com/products/server/raid/index.htm) It says " And since IntelĀ® RAID is powered by LSI MegaRAID* technology, you get all the new enhancements such as solid-state drive (SSD) support, improved data protection with SSD Guard*, and increased energy efficiency with the new Dimmer Switch* option."
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