RAID

Message

First Light · #1 Post by **First Light** » Sat Sep 06, 2008 7:32 pm

When you are configuring a unit and choosing components you have the option of:

1. Internal RAID - Not Enabled, or
2. Internal RAID - Configured by Lenovo

and the Hard Drives's available are all "Non-RAID HDD's."

What is RAID? and why would you want it, or not want it enabled with a Non-RAID HDD?

#2 Post by **jdhurst** » Sat Sep 06, 2008 8:25 pm

RAID stands for Redundant Array of Inexpensive Disks.

One basic method of RAID is Mirrored drives. You have two disk drives and one is a mirror of the other. If one fails, the other supports the load until the failed drive can be replaced.

The common method of server RAID is RAID 5 where you need at least 3 drives (but can have more) and one drive provides space for checksuming the drive contents. In a 3 drive array, you have effective capacity of 2 drives only. If a drive fails, you pull it out, put in a fresh drive and carry on. To do this, you need hot swap drives and a top notch controller. I use IBM servers, the RAID is top notch, and failed drives have been a non-event. I have a client who had a Dell server with RAID 5, and a low cost controller. A drive failed and the server collapsed. No data was lost, but the server did not come back up until the drive was replaced. The same client replaced the server with an IBM server. Time passed, a drive failed and the client did not know until I told them.

Do you need it? In a Server - without question. In a PC - I don't bother. I keep my critical data backed up so that I do need the cost or complexity of RAID. Good RAID is not cheap.
... JDH

bmn · #3 Post by **bmn** » Sat Sep 06, 2008 8:32 pm

jdhurst wrote:RAID stands for Redundant Array of Inexpensive Disks.

...

lol, inexpensive disks, i wish. more like RAIndependentDisks.

#4 Post by **Harryc** » Sat Sep 06, 2008 8:43 pm

Actually jdhurst is correct.
http://en.wikipedia.org/wiki/RAID

bmn · #5 Post by **bmn** » Sat Sep 06, 2008 8:51 pm

Harryc wrote:Actually jdhurst is correct.
http://en.wikipedia.org/wiki/RAID

interesting, i've always referred to it as i stated above. i guess it can be either, thanks for the info.

#6 Post by **jdhurst** » Sat Sep 06, 2008 9:00 pm

The first time I used RAID was with multiple arrays of 8 drives each. The drives were 3.5 inch industrial IBM drives and were vastly cheaper than the much larger S/38 counterparts.

I remember that batch of drives well. They were afflicted by stiction (which means they stood a good chance of not restarting if shut down). IBM came in once a day for several weeks and replaced one drive per day until it was all done. .. JDH

awolfe63 · #7 Post by **awolfe63** » Sun Sep 07, 2008 1:38 pm

The original RAID was developed in the days when "servers" used 8" and 14" drives. 5.25" "PC" drives were too small and too slow. RAID was developed to provide more speed and reliability from groups of these "inexpensive" disks. Very similar techniques had been used in servers and mainframes for DRAM for decades to increase speed and reliability.

barrywohl · #8 Post by **barrywohl** » Wed Sep 24, 2008 7:31 am

The W700 I'm configuring in my mind would have RAID 1 with two 320GB / 5400 RPM drives.

Wouldn't this give me fairly good speed and continuous backup so I wouldn't need off machine backups except to protect from theft or dropping the thing in a swimming pool?

In addition, I could upgrade to 300 GB 7,200 rpm drives when these become available.

Am I on track?

#9 Post by **jdhurst** » Wed Sep 24, 2008 9:31 am

barrywohl wrote:The W700 I'm configuring in my mind would have RAID 1 with two 320GB / 5400 RPM drives.

<snip>
Am I on track?

It will probably work. However, RAID wants speed, so you might wish to consider 7200-rpm drives if that is feasible.
... JDH

#10 Post by **erik** » Wed Sep 24, 2008 9:43 am

barry-

RAID 1 will give you write speeds identical to the native drives but read speed will nearly double.

RAID 0 will net faster read and write speeds at the sacrifice of redundancy.

RAID

RAID

Who is online