Raid5/Raid1 Hot spare setup and questions 1

[DrB0b]

Hello all,
Ive searched around and read some helpful posts but am still curious if my ordeal is going to be a difficult one. First things first, the hardware:
Systemax 5500 2U SAS Server w/
3 147GB Seagate SAS Raid5 PN:ST3146356SS
12GB RAM
Adaptec 3805 Raid Controller
Server 08

Right now as it sits, there are no backups or hot spare set up. Was looking at ShadowProtect4 server or Acronis for that but that's another post all together. After I get the backups running I want to setup a Hot Spare but I have this problem:
The HDDs installed are discontinued from the manufacturer, as are the Fujitsus of same size in our other server running Raid 1. We have a corporate account set up with Tigerdirect and they recommended we go with the new 300GB ones from Seagate. Ive been told that you have to use similar size drives or issues will occur. I can purchase the original seagates listed above from some other random google searched companies but not sure if i should just upgrade to the 300GBs for extra storage space anyway.
If i was just installing a Global Hot Spare of the same size, all I would have to do is physically install it and use ASM to tell it that it is a spare, correct?
I read a few of SPI200(or similar usr name) posts and he claims that you can install a bigger drive regardless of raid setup and it will rebuild as the original sized partition. Then you could extend the volume and receive the increased GBs from the bigger drive. Wondering if that's correct or is there something I'm missing.
Ideally I would like to, if possible, set a 300GB as a Global Hot Spare and when a drive does fail, after that 300 is rebuilt into the array, upgrade the other 2 drives to 300s and resize the volume to accommodate the growing needs of our server.
Please let me know if any or all of the info listed is correct or should I just buy like 20 of the 147GBs while I still can and hope our server space requirements dont grow too fast??
Thanks all

 

[technome]

I read a few of SPI200(or similar usr name) posts and he claims that you can install a bigger drive regardless of raid setup and it will rebuild as the original sized partition. Then you could extend the volume and receive the increased GBs from the bigger drive. "

Nope, at least with most raid adapters on the market.
With raid 5, to expand a raid 5 volume, you need to add the drive to the array (not replace), as in adding another 147 gig drive giving you (4) 147 gig drives. Then you can incorporate the added disk's space to increase the original volume's size
This is not the same as adding larger drives to replace failed or pulled drives. If you eventually replace all the original drives with larger drives (assuming new disks same size), you can not increase the original volume size by any means but the unused space on the new drives could be used to create a new volume (think of it as a separate hard disk).

Most of the time (say 95%) you should not have a problem using hard disks which are larger then the original array disk. There are occasions where firmware conflicts cause different make/models not to play well together, but it it is rare.
As you have found out, original make/model/size drives get hard to get, more expensive, as time goes by. Go for the 300 gig drives, make sure they are new retail drives (5 year warranty, verify warranty at the Seagate site), NEVER buy refurb/recert drives for use on hardware raid adapters, they have a very high failure rate; avoid OEM drives as they can become warranty issues, and at best 3 year warranties. Purchase extra drives NOW if you have the resources and plan to maintain this server for a few more years.



"all I would have to do is physically install it and use ASM to tell it that it is a spare, correct?"
Yes, pretty simple


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[DrB0b]

Thanks for the reply, I was actually able to find new replacement with 5 year warranties on the same 147GB drives and bought 2, one for a hot spare in each server. I will definitely go with bigger drives come upgrade time.
Thanks for elaborating on the drive swap issue. I didnt think you could do it that way and was glad someone confirmed my skepticism before I tried it and broke things. It is good to know that you can replace a drive with a larger sized one and it will still function at the original size and could use the rest of the space for an additional volume.

"Silence is golden, duct tape is silver...