Do I really need a battery backup?

D

DDuckMan

Limp Gawd
Joined
Mar 10, 2007
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I am planning WHS server that will have a single RAID 5/6 array for the OS and storage. I also have an active UPS.

I gather that I will need to enable write back caching to have reasonable write performance. I want to minimize the risk of data loss, so it sounds like should have a battery backup. Is that really necessary if I use an active UPS?
 
as long as your UPS can kick in fast enough, but a slight interuption could ruin any data if the system even breifly loses data

what raid card are you going to use?
 
The UPS seems to work very well, seamlessly compensating for brief losses of power. However, with the frequency that WHS writes to the disks it sounds like it would be safest to have the battery. Some say it needs to be replaced yearly. Is that really true? I thought lithium batteries generally last at least 2-3 years.

The whole idea of spending over 100.00 on a battery, remembering to do it, and cracking the case each year has me rethinking my plan for using RAID in my server. I would like to set it up and basically be able to forget about it until I need more space.

It's funny, I asked my brother who is an IT guy for a small government office what he thought. He has several RAID 5 arrays in the office and didn't know anything about write back caching and battery backups.
 
It's funny, I asked my brother who is an IT guy for a small government office what he thought. He has several RAID 5 arrays in the office and didn't know anything about write back caching and battery backups.
Click to expand...

I dont have a clue about the workings of raid either, im not the hardware type of person lol, all i know is what raid does and how it works etc..., all the servers i work with have proper raid cards with crap loads of cache nd battery backups etc... but all i care about is that the adapter does the job.
 
You are safe with the UPS option with no battery backup unit (on the controller) as long as the system is properly configured to shutdown in the event of a power failure AND the UPS provides ample time for all writes to complete and the shutdown to execute. Unless you are really taxing the server (and if you're using WHS you probably are not), all you need is maybe 5 minutes tops for a shutdown to complete.

On another note... If you are using WHS, you are kind of limiting the usefulness of the Drive Extender (DE) by setting it up with the single RAID5/6 array. It actually likes to have single drives and the DE service takes care of making them appear as your single large drive, thus enabling you (in theory) to add/remove drives, even of varying sizes, on a whim. It also can take care of the duplication on a share by share basis for you.

On yet another note... If you were trying to go the large array route to avoid the possible file corruption issues with DE (if you didn't know about this, you need to read here). You are going to be limited at install to 2TB due to the MBR limit. Now you can recover anything above 2TB after install by making additional partitions; however, then DE comes into play again and you are back to square 1.

Finally, on a WHS note only, it likes to be installed on a large(st) drive as it uses the first drive as a temporary landing point for copied files. I will spare you my personal feelings about WHS. :D

Sorry for the long somewhat meandering reply, hope some of this info it helpful.


 
Thanks, very helpful. I was starting to think that if larger server systems (which I am sure are protected by a UPS) use battery backup for their RAID cards, I should too. I am not sure yet if the UPS client will work properly on WHS, so I am thinking I should use a battery at least initially.

As far as the RAID SLV, you are right on. The DE bug is supposed to be fixed in June, but the fix is not even in beta yet. My current server is overflowing to my clients with data and is showing its age with a recent power supply failure and flaky USB functionality. I don't think I can wait for a fix that may or may not be out in a couple months.

I was going to start by breaking the array into two volumes, presenting one to WHS and saving the other until I run out of space again. Hopefully the corruption issues will be solved by then and I can safely give WHS multiple volumes. From there I would just add new disks to the array as needed and present them as new volumes to WHS. The RAID setup may be guilding the lilly at that point, but I figure it would still give additional protection, especially with RAID 6. Also I would be able to skip the mirroring feature.

If that would be a flawed setup, I am all ears.
 
You mentioned "clients" so one other thing to think about is if this is less for home use and it's actually more a business type application, you may want to seriously consider going to a full up Windows 2003 setup, maybe the small business edition would work well for you or just the 2003 standard.

The software does cost a bit more, maybe 2.5x for SBS, 4x or so for the 2003 standard, but you then get the full functionality and reliability of a business class OS and you don't have to worry about the flakeyness of DE in home server.

Just something else to think about.
 
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