DSM-G600, DNS-3xx and NSA-220 Hack Forum
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#1 2007-10-17 08:47:03
- deejcee
- New member
- Registered: 2007-10-17
- Posts: 1
Mixed drive setup (RAID1 + RAID0)
I'm looking at getting one of these units and throwing in a couple of 500GB disks.
Before I do though I wanted to understand what sort of capacity would be available.. is it possible to set the disks up as:
- 100GB RAID1 (for my critical must keep photos / college assignements / work data)
- 800GB RAID0 (for the rest of my junk .. I've got all my original CDs and don't mind having to rip them all over again in case of a crash 
)
In a RAID 0 setup if one of the disks failed would this result in losing all data from that partition? If so.. would I be better off setting it up as:
- 100GB RAID1
- 400GB
- 400GB
Cheers
DeeJCee
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#2 2007-10-17 10:14:50
- fickle
- Member
- From: Melbourne, Australia
- Registered: 2007-09-10
- Posts: 249
Re: Mixed drive setup (RAID1 + RAID0)
you (from my understanding) can only do
with your 2x 500gb disks
RAID 1 (both mirror) single volume (500gb) Volume_1 @ 500gb - recommended
OR
RAID 0 single volume (1tb) Volume_1 @ 1tb - not recommended
OR
Separate volumes (2x 500gb volumes) eg, Volume_1 @ 500gb & Volume_2 @ 500gb - recommended
unsure what JBOD still is.. but im sure someone can reply to this and correct me
just did a search on JBOD, you will end up getting
similar to RAID 0 but data can be recovered if a single disk fails (as data is not striped across both disks). normally JBOD is used when drives are not the same eg, 10g & 20gb to make 30gb.. where raid 0 will only take you to 20gb (but data loss completely)
SO
JBOD single volume eg, Volume_1 @ 1tb - somewhat recomended
Last edited by fickle (2007-10-17 10:25:25)
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#3 2007-10-17 15:10:13
- fordem
- Member
- Registered: 2007-01-26
- Posts: 1938
Re: Mixed drive setup (RAID1 + RAID0)
First - JBOD - Just a Bunch Of Disks - what this means can vary according to who is describing it. I've seen the term used to describe a collection of unrelated disks, and I've also seen it used to describe a single volume with the aggregated capacity of a number of disks. This last is similar to RAID0 except that the drives are concatenated or spanned rather than striped and there is no perfomance advantage.
RAID0 gets it's performance advantage by writing the disks alternately, "spanned JBOD" will write to the first disk until it is filled and then switch to the second, etc. It is unclear if files larger than the capacity of a single drive can be stored with spanned JBOD, and it supposedly has the advantage that if a single drive fails, the data on the remaining drive is still accessible - note the use of the word supposedly.
The DNS-323 uses JBOD as concatenated or spanned disks.
Next - RAID/JBOD options - the DNS-323 will allow you to choose the size of your RAID partitions, it does not require you to use the entire drive, but the only option for the remaining space is JBOD. Assuming 2x500GB disks you could have a RAID partition using 100GB in either RAID1 or RAID0, but the remaining capacity will formated as a single 800GB spanned JBOD partition. You do not have the option of choosing to have a 100GB RAID partition and 2x400GB separate volumes.
Finally - advisability
100GB RAID1 (for my critical must keep photos / college assignements / work data)
Do NOT consider RAID1 to be a substitute for backup - if it's critical, back it up to some other form of storage - the purpose of RAID1 is to reduce the downtime impact of a failed disk, it is NOT meant to be a form of backup.
Earlier I indicated that spanned JBOD has the supposed advantage that in the event of a failed disk, the data on the remaining disk will still be accessible - this has not been my experience with the DNS-323, maybe my test methodology was incorrect, maybe it will work for you - however with no performance enhancement, it is not an option I would use.
By the way - this post assumes that you are creating drives using the admin web pages - if you're using telnet and directly manipulating the unit, your results may differ.
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