My past experiments with RAID just taught me I don't know enough to be able to secure my data, so I thought a Drobo would be a good solution. I've never got on with it much to be honest.

I had 3 2Tb drives and a 1Tb but filled it up so replaced the 1 with a 2. That was 3 days ago now and it's telling me it still needs 3 more days to rebuild itself. That is 6 days of continuous hard drive access. That can't be normal ??? I know 4Tb of data is a lot but 6 DAYS !!!

Cheers

Cris

The Drobo uses RAID just like almost every other device out there, they just hide it behind some ugly hacks. Since you started with 3x2TB drives, and 1x1TB drive, the Drobo was striping together 2 RAID 5 sets. The first RAID 5 used 1TB from 4 disks, then the second RAID 5 used the remaining 1TB of space on the 3x2 disks.

When you yanked the 1TB and replaced it with the 2TB, the Drobo will keep the 2 RAID 5 setups around, expanding the second one to take advantage of the new space on the new disk. It's having to rebuild the first one, as 1TB of the 4TB is gone, so this involves lots of checksum calculations to piece together all the missing data. It then has to restripe the second RAID 5 to use 4 disks instead of three, so the entire second RAID set has to be recalculated for the new setup.

Here is some ASCII art to try to explain it better:

The X represents where data has to be rewritten and rechecksumed, basically 5/8th of the data.

I can't find specs on the initial Drobo, but the second gen device is specced to have a 500mhz Marvell processor, and that was an upgrade to whatever the first one has. It's going to take that processor a while to recalculate everything.

That seems unusually long. When I replaced a 1.5 with a 2TB in my 5.5GB (6 disk) ReadyNAS RAID6 array it took somewhere in the neighborhood of 6-9 hours.

Thanks, that goes a long way in my brain to explain what is happening

I have the FW800 model, which I think means it's 2nd generation. Overall with the Drobo I am amazed how slow it is at everything. I no longer use it for day to day use, it was just too slow. It acts as a massive Time Machine now and therefore my 3rd point of backup. It's not much good for anything else.

I know Photographers who use one with Lightroom and swear by it, but I think there is a little emperors new clothes going on. With the stock fan it's so noisy it's unture, and both read and write speeds slow Lightroom to the point I couldn't see the point in having a Mac Pro waiting around all the time for the Drobo.

But thanks for the explanation, I guess I'll just leave it for a couple more days

Cheers

Cris

Just got back from a weekend away from home, the Drobo has finally rebuilt. From what I can tell it took 6/7 days to complete.

I need to review my entire backup policy again, does any one have any strong views on using this to make a nice NAS out of...

http://h10010.www1.hp.com/wwpc/uk/en/sm/WF02a/15351-15351-4237916.html

They are doing £100 cashback on them at the moment which makes it very attractive, especially when I already have 4 1Gb drives ready to throw into it!

Cheers

Cris

Wow, thats a cute little Proliant. It's not using a storage controller I recognize as a SmartArray, so I can't comment on the reliability. Specs only list Raid 0 and 1, so at most you will have 2 TB worth of usable space with your 4x1TB disks. You could always do software raid 5 though to get 3TB.

With no OS out of the box, it would be just like turning any normal PC into a NAS. You can look at options ranging from Windows Home Server (not recommended since MS can't seem to implement and keep a drive expanding strategy), and unix based ones like FreeNAS.

I think I'd go with FreeNAS, I've tried to run that before but found the hardware I was using to be too noisy. I liked the software. One feature I really like about this microserver is the fact it has an internal USB socket, making booking off a USB key really easy!

Speed wise do you think this combo would beat a cheapo 4 Bay off the shelf NAS ??? I have some more RAM I can put straight in to take it to 4Gb.

If I build a software RAID5, could I expand it in the future by adding 2Tb drives as required ???

Cheers

Cris

On Linux you can, but since FreeNAS is based on FreeBSD, I think the answer is no, you have to backup, rebuild and restore. That's the recommendation in their FAQ. The people who are growing RAID arrays under FreeNAS all seem to be using RAID1. You might want to take a look at OpenFiler, which is Linux-based, if you prefer to use RAID5.

From memory, OpenFiler would let you do stuff like that.

Speed wise, yes. It looks like the processor in it is quite a bit more powerful then most NAS CPUs that use Atom chips. Though even an Atom doing software RAID is likely to rebuild way faster then your current Drobo.

NAS wise, the ReadyNAS Pro would be the product to compare to the MicroServer. It uses a more capable Core processor instead of the Atoms used in the ReadyNAS Ultra line.

As for expansion, can't really say myself, as I haven't kept up with the NAS distros in a while. I was under the impression FreeNAS 0.7 used ZFS as an option, but I don't have practical experience expanding ZFS.

The latest version of FreeNAS supports ZFS. Can't you easily expand ZFS volumes?

Edit: Tom beat me to it.

The Drobo will stay as my TimeMachine drive. This NAS will act as the 3rd data storage point for incoming RAW files into my workflow (main harddrive, Drobo via Time Machine and new NAS in another part of the house). I'd also like it to run as a media server for iTunes and my Squeeze boxes.

I this this will be a much more cost effective solution, and it's not so mission critical so I think I'll go ahead. Software wise I think both will run SqueezeServer, so which would be easier to run for a numb skull like me ???

Cheers

Cris

Yes, but expanding the volume is a different exercise than expanding the RAID system the volume is sitting on. The mentioned RAID1 expansions being done with FreeNAS are ZFS volumes.

I thought part of the point of ZFS is that you just threw raw drives at it and it handled data redundancy, instead of having to rely on traditional RAID. Is this not true for how FreeNAS used ZFS?

Ah, interesting. I'm not really that familiar with ZFS.

I thought so too, but using it's own special RAID, RAIDZ Currently there's RAIDZ, RAIDZ-2 and RAIDZ-3. All the info you need is here. Interesting stuff. It's a real shame they made their licence incompatible with Linux.

That's why you need Debian GNU/kFreeBSD.