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Koil
Premium
join:2002-09-10
Irmo, SC
kudos:2

JBOD to RAID5 using the same drives

(Mods, please feel free to move this to a more appropriate location if one exists)

Currently, I have 2 1.5TB drives. 1 is completely full and the other about halfway.

I could purchase 3 additional drives, bring the count to 5 1.5 drives.

I would like to put them in RAID5. Assuming all things being equal on the drives, is it possible to bring the 2 drives that I already have (containing data) in the 5 Disk RAID5 config without losing the data?

I don't care if its a lengthy process, and it seems like it could be done by re-writing blocks at a time, but would like to see if anyone here has ever tried this, or has experience in doing so?
--
I am only one, but I am one. I cannot do everything, but I can do something. And I will not let what I cannot do interfere with what I can do.- Edward Everett Hale

My Blog - Raising Connor



koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23

1 recommendation

I have never seen this accomplished on any consumer-grade or even small business-grade RAID controller. Heck, you can't even do this with ZFS. Your idea of "how it could be done" is a bit flawed (rather not get into the technical details), even though I do understand where you're coming from.

You *might* be able to put the new 3 drives into a RAID-5 array, leaving the existing 2 JBOD, then copy the data over from the existing 2 to the new 3, then somehow (not sure if your controller supports doing this) after the copy is done, adding the additional 2 drives as part of the RAID-5 array.

You should engage your RAID controller vendor for questions like this -- they'll be able to help you.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.



Koil
Premium
join:2002-09-10
Irmo, SC
kudos:2

I'd thought about the 3 add 2 scenario, as well.

I work with enterprise arrays and tape libraries, and going by the cost of those things, there is no way I can afford either of those solutions, even in a scaled down "home" version.

So, let me ask you this, as I respect your knowledge in this area...RAID5 isn't as good as a backup (and yes, I know they're not the same thing at all), but in a home environment and talking about this much data, what would YOU use for a backup solution (without spending a King's ransom)?
--
I am only one, but I am one. I cannot do everything, but I can do something. And I will not let what I cannot do interfere with what I can do.- Edward Everett Hale

My Blog - Raising Connor



koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23

1 recommendation

Rather than tell you what I would use, how about I tell you what I do use?

For my actual storage system, I use the ZFS equivalent of a RAID-1 array consisting of 2 1TB drives. For my backups, I have a standalone 2TB disk -- no RAID or other nonsense involved (and there's damn good reasons for this, the biggest being: the last thing you want to deal with in the middle of backup restoration is "RAID controller nonsense"). My backups are done nightly. All the drives involved are WD Reds.

If I had more hot-swap bays in my chassis, I'd be using the ZFS equivalent of RAID-5 across either 3 or 4 drives, and keep the existing backup model (a single disk -- although I might need a 3TB drive, or if I needed the space, possibly move to the ZFS equivalent of a RAID-0 array, but I'd rather not).

Don't let my use of ZFS try and persuade you to use it -- ZFS has basically zero bearing on why my storage setup is the way it is. If folks want to use BIOS-level RAID that's perfectly fine too (and I've used that too).

In general I tend to recommend folks who need lots of space reconsider their need for such, i.e. ask yourself the question "do I really need that much space all the time?" Most of my own usage, for example, is taken up by ISO images and videos. Every year I go through my array and offload onto a spare hard disk (or DVDs if the data will fit on them) the stuff I don't tend to use. This allows me to keep my array sizes down, and in turn greatly diminishes the complexity of my setup.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.



Hagar

join:2004-10-31
Sunnyvale, CA
Reviews:
·AT&T U-Verse
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reply to Koil

I do the same Koitsu. 2 750GB and a 2TB for the backups no RAID to avoid any RAID controller issues during restores. E.g each files exist on two disks.

I have another rule. When I buy a new HD it needs to be twice as big or bigger than the previous drive it replaces.

I would look at 3 TB for your new drives. I use my old drives for offsite backups. E.g take a backup and store it offsite.


n_w95482
Premium
join:2005-08-03
Ukiah, CA
reply to Koil

I have a four 1 TB RAID 5 setup with a hardware controller, with a 3 TB external drive for offsite backup. No issues here . I had one drive fail about two years ago, and it limped along on the remaining ones with no dramatic loss in speed. Once I got the RMA replacement, I plugged it in and the controller automatically rebuilt the array.
--
KI6RIT



Kilroy
Premium,MVM
join:2002-11-21
Saint Paul, MN

1 recommendation

reply to Koil

The short answer is NO.

Normal procedure for any RAID change is:

1. Back up.
2. Make changes.
3. Format new array.
4. Restore.

I've never seen anything that would allow you to add drives and then change the array type without a full loss of all data on all drives involved.

You might want to spring for a 3TB disk to copy all of your data before you do this. Then add the disks and restore. Personally I would buy three new disks and put them in RAID5 and not add the two you currently have as you may see issues mixing drives.
--
“Progress isn't made by early risers. It's made by lazy men trying to find easier ways to do something.” ¯ Robert A. Heinlein



Jan Janowski

join:2000-06-18
Skokie, IL

1 recommendation

reply to Koil

Make sure they all have same firmware, or don't bother.... Oh yes, purchase ONE MORE DRIVE than you need...

Backup your data to other drive, which you may also need to purchase....

Once your data is secure... Verify your drives are same model, and identical firmware

Make your raid 5, keeping one drive out intentionally. put a small amount of inconsequential data on your new Raid.

Test your raid 5... pull a drive, forcing it to adapt... Learn the recovery procedure (This drive becomes your tested spare drive)...

When your comfortable with this procedure, Add the extra new drive... Learn the rebuild procedure.

OK with Learning and maintenance? Dump your data back on the new raid... The drive you used for temporary storage becomes your new backup.

Don't go cheap. Don't bypass steps by not verifying firmware on the drives....
And ABSOLUETLY Have one extra drive in stock, because there is nothing worse than needing to purchase a new drive 5 years later, only to find it isn't made any more!
--
Looking for 1939 Indian Motocycle