[Webinar] Streamline your web hosting managementRegister Today

x
?
Solved

Riad 5 hot spare

Posted on 2008-02-06
14
Medium Priority
?
458 Views
Last Modified: 2013-11-14
Hey

setting up a new server with 6 400GB SAS drives.  i have an option for a hot spare.  do i need this?  can i just use all 6 drives in the raid 5?

thanks
0
Comment
Question by:phrea84
  • 4
  • 4
  • 3
  • +1
14 Comments
 
LVL 19

Assisted Solution

by:SteveH_UK
SteveH_UK earned 500 total points
ID: 20834586
You can do either.  I tend to use hot-spares because it affords some flexibility in the case that you can't get to the machine, such as over a holiday period.  It also buys you a bit of time to get a new disk on site.

Other administrators think they're a waste of money.  It's a question of balancing risk.

If you had three drives in your array, then that's quite a lot of wastage, but with five drives it is less wasteful and may be a good choice.

Ultimately, you need to decide what risks are acceptable to your organisation and how quickly you can replace a failed disk.
0
 
LVL 69

Accepted Solution

by:
Callandor earned 1000 total points
ID: 20834597
You can use all 6 drives as part of the RAID-5, but it is better to have a hot spare to automatically kick in if a drive fails on you.  Less downtime is a good goal in running servers.
0
 
LVL 4

Assisted Solution

by:pghzooit
pghzooit earned 500 total points
ID: 20834623
this is all about redundency vs cost
raid 5 you will loose 400GB
raid 5 + you loose 800GB
we have yet to use the raid 5 +, but its the more redundent option.

so its your choice, but as long as you have good backups and the drive can have down time. I would choose raid 5.
0
Take Control of Web Hosting For Your Clients

As a web developer or IT admin, successfully managing multiple client accounts can be challenging. In this webinar we will look at the tools provided by Media Temple and Plesk to make managing your clients’ hosting easier.

 
LVL 2

Author Comment

by:phrea84
ID: 20834684
what if just set up a raid 5, no hot swap, and buy an extra 400GB drive that i can throw in if needed?  this would give me the most space and a good backup plan if needed, right?
0
 
LVL 69

Expert Comment

by:Callandor
ID: 20834773
Depending on your controller, a hot spare can be used automatically if a drive failure is detected.  Your plan requires downtime to replace the faulty drive, which may or may not be doable - it depends on your server uptime requirements.  If your users can live with the downtime to replace a drive, it is a workable solution.
0
 
LVL 4

Expert Comment

by:pghzooit
ID: 20834787
that is tricky at best, I dont recomend that .
0
 
LVL 19

Expert Comment

by:SteveH_UK
ID: 20834871
There isn't much point in buying an extra drive to use as a hot spare and then not use it!  However, if the drive can be shared between multiple servers and you have hot disk swapping then it can be a good solution.

Personally, I'd still attach it to an important server and then move it if it was needed elsewhere.
0
 
LVL 69

Expert Comment

by:Callandor
ID: 20834910
Tricky?  It's standard procedure if a drive failure is detected in a RAID-5 - bring down the server, boot it up into the controller to detect the failed drive, bring it down to replace the drive, and boot it up again with the new drive and let the array rebuild itself.  Some controllers allow you to work with the array in a degraded state, while others require the array to be rebuilt before using.
0
 
LVL 2

Author Comment

by:phrea84
ID: 20834933
thanks all for the help.  im gonna build it without the hot spare and take my chances with a 2nd drive on the side.
0
 
LVL 19

Expert Comment

by:SteveH_UK
ID: 20834942
Again, I'd recommend against using software RAID, and if you are using an enterprise class RAID controller then you should expect to be able to rebuild the array online and to use hot-swap disks.  I agree with Callandor that this should not be tricky, and I'd also recommend that you get to know your RAID controller and software inside out.  You shouldn't be making guesses in a real disk failure situation.
0
 
LVL 4

Expert Comment

by:pghzooit
ID: 20834945
I was sayiing that it was tricky to re-RAID a drive, if thats a word.
you can, but I wouldnt .
having RAID 5 then chaing it to RAID 5 + online spare.
0
 
LVL 2

Author Comment

by:phrea84
ID: 20834966
i have a dedicated RAID controller that i will be using, so it shouldnt be an issue.  i dont think its possible to go from a raid 5 to a raid 5 + spare without breaking the raid and having to format the drives and rebuidling, is it?
0
 
LVL 69

Expert Comment

by:Callandor
ID: 20834991
It all depends on the controller - Areca, for example, provides the capability to add a hot spare to an existing RAID-5 without rebuilding it.  It's not as bad as changing the RAID type, which typically requires backing up, changing the configuration, and restoring from backup.
0
 
LVL 19

Expert Comment

by:SteveH_UK
ID: 20835029
It would be unusual for you to have to rebuild an array to add a hotspare.  I'd be very surprised to see such a 'feature' ;)
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The question appears often enough, how do I transfer my data from my old server to the new server while preserving file shares, share permissions, and NTFS permisions.  Here are my tips for handling such a transfer.
What is the biggest problem in managing an exchange environment today? It is the lack of backups, disaster recovery (DR) plan, testing of the DR plan or believing that it won’t happen to us.
This video teaches viewers how to encrypt an external drive that requires a password to read and edit the drive. All tasks are done in Disk Utility. Plug in the external drive you wish to encrypt: Make sure all previous data on the drive has been …
Despite its rising prevalence in the business world, "the cloud" is still misunderstood. Some companies still believe common misconceptions about lack of security in cloud solutions and many misuses of cloud storage options still occur every day. …
Suggested Courses

590 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question