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smccain 11-30-2010 12:32 AM

RAID recommendation request
I've been asked to set up an 8TB server.
In the past, I had some difficulties getting Linux to recognize more than 2TB on a single volume. I'm guessing I can get past that using reiserfs and LVM.

But ... I'm wondering if anyone has any suggestions for a good-quality RAID card that's known to work well on a CentOS-based server housing nine 1TB drives ... or four 2TB drives? (I'm looking at SATA, by the way).

Thanks in advance for any knowledge to be shared.

mesiol 12-05-2010 05:18 AM


all hardware recommendations depends on what you are trying to do with your disk space. What are you planning? Housing a database? running highly loaded samba? what level of fault tolerance are you looking for? how many IO are you planning?
Are you sure that you will use SATA drives and not SCSI or FC?

Be aware the more disks you use the more IO can be done, so you better will have 16x500GB than 4x2TB disk to stripe IO across more spindles.

There is no overall solution which will fit to any use case. So please be more specific.

smccain 12-06-2010 01:08 PM

Thanks for your response, mesiol. I apologize for my lack of specificity.

This is just going to be a huge samba share, used by clients equal parts Windows and Macintosh -- four of each client type.

I think I'm going to go with a quantity of ten 1TB drives.
Traffic to this server will be very hit-and-miss.

Access will be primarily the transfer of 10- to 150GB graphics (primarily photoshop .PSB files) from and to the clients. The users will (at least, the users are *supposed to*) copy the files to their local hard drives, do their work locally and then then transfer the finished work back to the server upon completion.

Typically, the users will copy to their local drive on a Monday to work on them, and then drag the files back to the server at the end of each day of the week, so the latest versions of these files can be rsync'd to other locations in the nighttime hours.

In other words, I guess this is just a kind of samba warehouse. We do not need database or streaming-video-from-server-level performance.

Again, I appreciate your response and any advise you can give based on the above. And, certainly, as I am the begger for expertise in this situation I'm happy to offer any other relevant details.



mesiol 12-07-2010 01:21 AM


one of the key values will be the traffic per day/hour. So calculate as exactly as possible how many traffic will go to your fileserver. There is a large difference between 10GB and 150GB especially when this traffic will occur in a short time frame (morning 8-10a.m. and evening 5-6p.m.)

Let's do some easy calculation:
Max: 150GB within 2 hours ~ 2.5 GB per minute = 41MB/s
This will require more than enduser SATA disk in a small machine.

Min 10GB in 2h = 150MB/min = 2.7MB/s
This can be handled by nearly all small NAS system.

So you see there are extrem differences. Best you will re-ceck this values.

chickenjoy 12-07-2010 01:49 AM

1. Whats your network speed? (like are you using desktops, switches, routers that supports gigabit ethernet?)
-- to avoid traffic congestion; maybe you can set a per user policy in samba to only allow them to access the server on certain time frames.
2. Is the hardware your using a white box or a branded machine? (for stability purposes)

Dani1973 12-07-2010 07:47 AM

If you want a good SATA raid controller I would advice Areca, they are very reliable, mostly not of the 'fake raid' type and if you look at any benchmark tests they are always in the top.

Still it also depends what's the budget, if you have the budget go for a real storage server ;)

Only thing that 'scares' me in your request is that it seems that you haven't really decided about the raid level yet and are still a bit confused about the 'numbers' of needed bandwidth and IOs

jefro 12-07-2010 05:26 PM

Buy an enterprise level (and they are all hardware raid) card and it should work fine.

Plug in a good enterprise level nic like intel's and set them up at least for some of the features they offer.

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