RAID specification / purchase help!

[jimstein123]

Hello all,

I'm looking to build a giant storage system and I'm deciding between the 3Ware 9650SE-24ML, Areca 1280ML, and Adaptec RAID 52445 for my RAID card.

After looking at it, I have no strong feeling for any one of them, maybe against 3ware since it did not outshine its competition in any particular area.
-The Areca initially has 256MB memory, compared to 3ware’s and Adaptec’s 512MB, but Areca has the ability to expand to 4GB DDR2 DIMM.
-The Adaptec has a dual core 1.2 GHz processor while Areca only has a 800 MHz, 3ware did not announce its processor speed.
-Also, Adaptec claims to have 3Gb/s Data Transfer Rate (380 MB/s), compared to Areca and 3ware’s 300MBps.
-All other features were comparable – similar software configuration solution, etc. They all cost about $1,100.

Between all 3, what do you guys think is the best spec'd? Is the advantage of buying 3.5 extra DDR2 DIMM (700% increase) greater than having 400 MHz speed of the Adaptec (50% increase)?

I guess all I'm really asking is: If I ran each card with RAID 6, which one do you think is the most stable and compatible with motherboards/hard drives, and what does the processor speed and the ram do for the RAID card?

Thank you for your help!

 

[SomeJoe7777]

The total amount of cache memory is important in terms of RAID 5/RAID 6 writes, but there is a point of diminishing returns. You may not notice much difference between 512MB and 4GB except with a very few specific applications. The difference between 256MB and 512MB is likely to be more noticeable, even if only in benchmarks.

The on-board processor speed is misleading, since the method by which the processor works is different between each of these controllers.

All of the transfer rates quoted are the same. They are the same 3Gb/sec (300MB/sec) SATA transfer rate, just expressed differently. That is also the theoretical full transfer speed to each drive, but each drive won't actually transfer data at that speed except from the drive's cache. Speed to/from the platter is much slower.

Though the feature list might be the same, the robustness of the drivers and software has an edge with the Adaptec and the 3Ware. The Areca is a notch below.

By the same token, the support is another factor. Again, Adaptec and 3Ware have the edge over the Areca.

You can't take the processor speed, cache size, and transfer rates and infer anything about the real-world performance. At the level of these RAID cards, the entire system has to be benchmarked as a whole. Even then, the synthetic benchmarks are only a guide, they don't have a perfect correlation with real-world application performance. I'm not sure where you were looking when you say the 3Ware didn't outshine its competition, but I can offer something of my own:

8x Seagate Barracuda ES.2 1TB 7200RPM, 3Ware 9650SE-16ML, RAID 5, P5M2 mainboard, Core2 Duo E4500, 2.2GHz, 4GB RAM, Windows Server 2003

I could do some other benchmarks like IOMeter's Web/File/Database benchmarks, but my server is doing a migration right now, so I'll have to wait until it's done.

I don't know how these benchmarks compare to Adaptec's or Areca's, but certainly the 3Ware seems to deliver.

Something else you might consider if you want to build a storage system that's this large is to consider an iSCSI or Fibre Channel SAN. These can get really expensive, but there are some entry-level models that work very well. On iSCSI, you won't get the raw transfer rates that Fibre Channel or these cards can give, but the IOPs can be very high. Check out the Dell PowerVault MD3000i. I have one of these hosting SQL database, Exchange server, and 6 VMs running under VMware ESX. It's very fast, and easy to configure.

 

[Hovaucf]

I know the 52445 outperforms the 3ware card, and I also know it's memory is rated at 533 not 400 you're thinking of the old 3xxx series. Anyways I agree though Adaptec or 3Ware should be the direction to go.

 

[jimstein124]

Thank you very much, both of you. I actually wanted to thank you for the information earlier, but I lost my password and had trouble retrieving it.

I am actually building this server for a high school as a network administrator. We recently got some funding and we're attempting to build a powerful server to be shown off during Parent's Night this coming school year. Each of the computer in the classrooms will be connected to a television and will be streaming high-quality videos of the kids in the school doing their work and having fun during the past year and the beginning of September. These videos shown to the parents will be a highlight of this year's Parents' Night.

So I just want to make sure that the RAID card is correct to be used for media streaming and storage. For that night, there might be up to 100 classrooms using the server at the same time. And even afterwards, we'd want to keep the data as safe as possible for the many years to come. (We do not get a budget for nice servers every year. )So I guess that quantity the card can output, the speed it is able to deliver per stream, and reliability/ high-uptime are the most important factors for me.

So with that in mind, which one do you think would be the right one for me?

Thanks again for all your help!

 

[SomeJoe7777]

Whoa, hold up there, holmes.

100 simultaneous streams? You kind of didn't mention this before.

OK, what type of file is being played back (.wmv, .flv, .avi, .vob, .iso) and how is this being played back (PowerDVD/WinDVD, Windows Media Player, some other media player, proprietary software)?

What kind of network connection will be available to the server? The clients?

What bitrate are the media files?

There's a whole host of other considerations that are way more important than the RAID card to allow simultaneous playback of 100 streams.

 

[ldiamond]

Could you please specify the reason why you want to be using RAID?

What applications will this server run?
Will it simply stream video?
Is it always the same video streamed everywhere? If so, its more of a networking problem here (you simply need to use multicast)

 

[jimstein124]

Thanks for the reply!

Specifically, the quality of the video recorded by the AV Club is done through some HD quality cameras, so I'm guessing the streams can go as high as 20 MB/s. (Some of the classrooms and the auditorium have projectors, so that's why we have a higher quality video.) Even though each of the video is only about 5 minutes long, chances are that the video would be played almost at the same time in the different classrooms. So I would like to account for the heavy load on the RAID card. All of this is being played back as .vob files. The network connections between the server and the clients will be done through wired Ethernet.

Unfortunately, it's not the same video everywhere, so I'm not too sure if I can try to implement multicast. The videos made specifically for different subject, so there's one for Math, one for Science, etc. , and a general video played in the auditorium and cafeteria.

Outside of this event (which will be yearly if it is successful), this server will also store files for teachers and students as well for access in the classrooms and the computer labs. The RAID card is there to keep the data safe and as one of the measures of backing up. I'm guessing that if this thing could do video streaming for this night, it can do file serving fine.

That's why I'd like to know which of these three is the best one for my application. But I think there's now an extra question of how many streams can be done at the same time with the limitation of the RAID card. If more than one server is necessary in order to successfully serve the videos to all the classroom, then I need to recalculate how the budget is going to be used.

Thank you once again for your valuable input!

 

[SomeJoe7777]

OK, .vob files are standard definition MPEG-2 encoded files meant for DVD. The maximum bitrate is 9.6 Mbps, but most .vob files are lower than this (7 Mbps or less).

It is common to film in HD using HD quality cameras then downconvert to SD for DVD.

Now, you need to find out specifically if this is what the video is, because if it's not, all these calculations I'm about to make will be off.

100 streams at 7 Mbps will be 700 Mbps. There's several considerations here:


1. Network. 700 Mbps is within the capability of Gigabit Ethernet. However, you will need a top-notch Ethernet card and top-notch enterprise switch to handle this traffic. I would recommend a Broadcom NetXtreme II, PCIe, with the TCP offload engine enabled. In fact, I would recommend that you use a dual-port version of this card, and put the two Gigabit Ethernet ports in an 802.3ad/LACP trunk. This will give you 2 Gbps from the server to the switch.

The switch needs to be a high-end enterprise switch supporting 802.3ad/LACP.


2. RAID card. 700 Mbps = 88 MBps, which is well within the capability of most enterprise RAID cards. However, to prevent problems, I would configure the RAID card as follows:

a. Enterprise-level card, 10K or 15K SAS drives, in a RAID-5 with hot spare or RAID-6, with a lot of on-board cache. (For example, AMCC 3Ware 9690SA). SAS drives will improve access times and responsiveness of the server, which is critical for time-based data like video.

b. When creating the volume/partition that will hold the video data, ensure you use a method of creating the partition that will cause the partition to be aligned to the RAID stripe boundary. For Windows servers, you can do this with the DISKPART command line utility. If you're going to use a Linux server, you'll have to look on the internet for the correct way to do this.


3. The Server.

a. Motherboard: You need a server-level motherboard with a server-level chipset. Do not attempt to use anything less than the Intel 5000 series chipset with Xeon processors. You will run into problems trying to internally move this much data around.

b. Processors: I would recommend not going light on processors. Two dual-core Xeons or a single quad-core Xeon with a 1333MHz FSB should be used.

c. Memory: Very important in a file server like this for caching. I would recommend 8 GB in a dual-channel configuration.


4. The OS:

a. Linux can obviously be used, but personally I would choose Windows Server.

b. Obviously, with >4GB of RAM, you will need to use an x64 version of the OS.

c. When configuring the file server, there are some tweaks to be done in the File/Printer sharing item of the Network connections control panel, and some tweaks to be done on the disk devices in Device Manager.

d. Enabling the TCP offload engine in Windows Server is specific - follow the network card manufacturer's directions.


Even with all this, I make no guarantee that this will work. This is pretty much the top-end single server you can build for this task, and the calculations show that it should be adequate, but there's no guarantees.

A primary concern is that even though 88 MBps sounds low, these will be essentially random accesses to the RAID array, not sequential. Under random access benchmarks, the aggregate MBps that the RAID card can do drops dramatically. 15K SAS drives will help a lot by reducing the random access time. Another thing that can help is increasing the number of spindles, since the RAID card can issue separate commands to each drive if they are not co-dependent. I would recommend that the array have at least 8 spindles.

To me, this really isn't the type of system I would attempt to build myself. You should really hire a storage consultant from one of the large computer service companies (HP, Dell, etc.) and get their advice. They will be able to give you some performance guarantees and ensure that the system can actually perform the required tasks.

 

[jimstein124]

Thank you so much for the help! I'll go digest this information for a bit.