XServe + XRAID + QLogic

[Tamino]

I have a fully populated XRAID box connected by two fibre cables to a QLogic Fibre channel switch. I added an XServe to the mix via the QLogic Fibre switch and I can mount the drive partitions on the XRAID fine. I then attempted to setup user home directories and it worked with my test account.
Now the trickey thing here is I need to have at least 12 more XSERVES to be able to access the share on the XRAID box. When I added a second server I could see the XRAID partitions fine, however I wasn't able to use the same share since the permissions were set from workgroup manager on the other box.

Did I do something wrong or am I totally wrong in thinking I can share one directory on an XRAID with 13 XServes?

[Go3iverson]

Whoa. Bad idea! You don't want to mount the same volume across 13 hosts without some sort of control. Think of it this way, what if they all write to the same blocks at the same time? Yeah yeah, file locking and whatnot, but still, this is a recipe for disaster and data corruption. If you want to make a single volume accessible to multiple hosts, Xsan is the way to do this (though not with home directories) as the metadata controllers will mitigate access.

Why do you want one share to be accessed by 13 xserves?

Michael

[Tamino]

What I need to do is bring all the user directories into a single data storage device (XRAID) I can do it with LUN Masking and connect each LUN to a server but I was trying to stay away from one server 0 one share.

You see, the problem is that we have 8 schools. 5 elementary, 2 Middle and 1 highschool. We want to keep all the student home directories in the following directory structure:

share the directory student
student/YOG2006
/YOG2007
/YOG2008
.............
/YOG2017
/YOG2018

This way once the student starts in Kindergarten, the data will stay on one place thrut he student's education thru the system. The way the old administrator was doing things was each school had a server and hhe was sharing YOG directories off them. Only problem was an elementary school would end up hosting a senior class and the data would overwhelm the Hard drive and in some cases the total number of AFP connections would bog down the servers so local users can't authenticate.

Plus the YOG2009 would be an elementary grade so you would have users connecting to the server from 5 different locations.

My problem stems from the Apple recommendation for only 100afp connections per server. I have been told by other ACSA's that if you bump the memory up to around 4GB you can get decent performance with up to 200 users.

I'm basing my connections on number of clients in each school. if a school has less than 100 computers than one AFP Home directory server will do. If the school has 480 then I'd need to have 5 AFP home directory servers. Now I'll have my user directories. So right now the way I calculate it. If I use LUN Masking with the XRAID I'll need 16-19 servers and I'd have to make 16-19 luns on the XRAID. What happens if I have to add storage to a specific YOG? With an Xsan I could just pop another XRAID into the san and configure it to expand my volumes.

So I guess the questions I need to ask is:
1.
Keeping the data storage structure mentioned above, Is it possible to create an XServer cluster where I can have up to 1,1500 clients connect at one time with one AFP path (i.e. \\thecluster\students\YOG2005 \\thecluster\students\YOG2018)?

2.
If I bind the two ethernet ports on an XServer to the same IP address, How much more bandwidth would I get and would it make any noticable difference in performance should I exceed the 100 AFP connection limit?

3.
If I have to bind 16 LUN's to 16 XServes, How easy is it to expand the capacity of the LUN if the need arises and if I can't expand it within the existing XRAID how hard would it be to add another XRAID to the fabric?
Could I expand the LUN across two XRAID boxes or would it be better for me just to move the directory to the new XRAID and redirect the LUN?

[Go3iverson]

So, couple things -

1. As I'm understanding, you aren't using the same path 18 times, but 18 paths as individual share points. That will work, since each host server will control their own point.

2. Is dividing up an XSR 16 times going to provide enough disk space for your students? Even if you got the unformatted, 7TB out of the RAID, you would be getting an average of under 500GB per server. How are you planning on dividing up the storage?

3. I'm not a big fan of spanning a volume across multiple controllers or XSR units. Conversely, I do like that practice when Xsan is in place, as that's what Xsan does and does well.

4. Link aggregation probably isn't your issue here, since bandwidth should be ample. It would more be overall load on the AFP server itself. I don't think 200 simultaneous connections is a number you should bank on. Have you considered portable homes? Those would reduce overall load a bit.

Michael

[Tamino]

Mobile homes would be to much. I'm trying to whittle down what I can from the profiles as they are too big as it is.

500 GB isn't that bad a partition since most of my servers were configured with only 80GB drives in them. I have 8 schools. All the elementary schools, except for one, can utilize one AFP Home directory server each. The two middle schools and the remaining elementary school will get two each. The high school will need 5 afp servers. Then I'd need a place to store user group data etc.

[Go3iverson]

Mobile homes would be to much. I'm trying to whittle down what I can from the profiles as they are too big as it is.

Just remember, if you lose an AFP server, one school won't be able to login. On a grander scale, if you lose a RAID controller or a fibre cable, you'll lose multiple schools, since login will fail without being able to hit the network home. PHD will allow you to be up, even when your down.