Final Raid5 questions before purchase

T

Tomson

Weaksauce
Joined
Nov 19, 2007
Messages
127
Long time lurker, used a great deal of good advice from here, thanks regulars.

I've had a couple questions about raid5 for sometime, and before I purchase my 8 port sataII card and setup a server theres 3 things I wanted to clear up, so I'd thought I'd try here :

1: Copying Array / Transferring Array

Scenario:

a. I purchase 5*500GB drives for my machine with an 8 port raid card.......... In 2 years time I decide that I want to replace (not expand) the array with 5*1tb drives​
To copy the array, what would be the best way? - Individually replace each 500GB drive with a 750GB drive and "Rebuild" until all 500GB drives are replaced with 750GB ones?

I thought a crude method would be to use a seperate machine, and just carry out a simple
network transfer, but this didnt seem practical - a) I'd have to buy/make another machine that I don't need + setup an array.


2 - Expanding Array

Scenario:
I purchase 5*500GB drives for my machine with an 8 port raid card, and 1 year later I decide to add another 500GB drive​

I have read about OCE (Online Capacity Expansion), seems great. Is it as simple as it sounds, i.e. attach
another drive and click a few buttons in the gui)? Are there particular versions of it that I should look out for
when purchasing a card?


3 - OS Placement

Seperate drive? or part of the raid array?​

I'm leaning toward seperate drive - I presume in a seperate drive scenario that the raid array has nothing to do with
the seperate drive? i.e. changing OS from Windows 2003 server to Linux or Windows 2007 server won't make a difference.


Any other advice related to the questions would be greatly appreciated.

Thanks in advance guys.
 
Q1. Easiest way would be to image the machine before adding the new hard drives. Shut down the machine and install the new drives. Reimage the machine to the new drives.
You card may allow for a hot swap of drives but I dont know if it will support a different size. Talk to the manf about this..

Q2. Most cards will have no issues with this

Q3. I'm not sure what your question is but I would definately put the OS not only on a different physical hard drive but also on a different array.

So your OS says is on raid 1 with 2 disks and your other raid 5 array contains the rest of your disks. This would provide good fault tolerance
 
1 - While this can technically be done and I have done it with a SCSI raid setup it is really not the proper way to go about expanding that available space. Really should backup the system and restore the backup. Some controllers will not even allow you to use the new unused space once all drives have been replaced - some will let you create a new array with the space - some will let you expand an existing array with the space.

2 - Really not sure as I've not messed with any sata raid controllers and on SCSI or SAS I'd have to do some reasearch on current controllers that have the options and abilities I'm looking for.

3 - Separate drive - mirrored if you like the idea of a little fault tolerance.
 
Thanks for the replies

In regard to Q1:

I know raid5 isn't for backup, but how (realistically speaking) could I backup a few tb's of data. Currently I have a lot of stuff on DVD so that is in part a backup, though it would take ages and ages to restore that much data from dvds.

Genuinely interested to know how people with raid5 servers with at least a couple gig backup.
 
The easiest ways to back up large amounts of data, short of enterprise-grade devices, are: (1) External drives (requires some software support for separating data onto multiple drives) (2) Second server.

I have a second server with a full backup of the primary.

We can dream about affordable HVD or some other large optical format, but reality is that drives are about the cheapest $/GB at this level.
 
To back up tons of data you need tons of space. I would go with a NAS unit that fits your needs.
You can get them in many different sizes from 1TB to several hundred TB. Its all about what you need and can spend
 
Couple of options for backing up that much data..... Get a couple few external 1tb hard drives, buy a NAS unit with enough space, borrow a bunch of friends computers and put on the network and use all their free space, go with a tape backup solution (what I did). Personally I like high end tape solutions but buying this sort of thing new can be very expensive - I have a graphics business with needs to backup about 2TB and keep the backups current so.... tape it is. I did cheap out though and bought a used 9 tape autoloader on eBay. The SCSI controller to run a decent tape drive is pretty cheap. In all I spent a little over a grand with the loader, tapes, and software to run the loader.

This is like the one I got but I picked mine up for right at $500 http://cgi.ebay.com/IBM-LTO-Tape-Au...ryZ39978QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
 
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hmm, this is all so costly :)

maybe i'll just go with raid6 and convince a friend that he needs a multi tb raid array as well, and drop my stuff on his.
 
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