DSM-G600, DNS-3xx and NSA-220 Hack Forum

Man that 343 looks nice!
Nice we can use Raid 5 now thats redundancy...

Last edited by nUll (2008-06-03 19:49:12)

nUll wrote:

Man that 343 looks nice!
Nice we can use Raid 5 now thats redundancy...

RAID5 offers exactly the same level of redundancy as RAID1 - your data remains available if one (1) disk fails - if a second disk fails before the first has been replaced and the resync completed, you will still lose your data.

RAID5 has the both advantages and disadvantages when compared to RAID1 ....

The advantage is effiency (from a storage point of view) you lose one disk's worth of space, in a four disk system that would be 25% of the space lost, as compared to 50% for RAID1

The disadvantages are ...

a) greater complexity - in the case of a system failure it is going to be more difficult to retrieve the data, you will need to move the entire RAID array (all the disks) as compared to just one disk in a two disk RAID1 array.

b) write bottlenecks - all writes require a checksum to be calculated and written to the disk.

This last can become a serious issue in multi-user database applications (where I doubt you'll find the DNS-343) where individual records are being accessed randomly, to the extent that some developers with whom I have done implementations will point blank refuse to install on a RAID5 system.

c) read access takes a performance hit if operating with a failed disk - the data can no longer be read directly, but must be extracted from the checksum data.

It would be interesting to see which processor is being used in the DNS-343 and to see how the read/write performace compares to the DNS-323, I'm also wondering if the DNS-321 is going to replace the DNS-323 as we know it today.

assuncap wrote:

The DNS-321 looks to have IP webcam support, could be a nice low end surveillance solution.
But is that the only difference for the 323?!
A better CPU and more Ram would be nice... and the case looks cool too.
We have to wait for the first reviews.

You can do webcam support with "compatible IP cameras" with the DNS-323, D-Link's DCS-950 & DCS-1110 can both record to any NAS, I don't know if you realize that all though the IP camera is shown in the sketch, it is not mentioned anywhere in the text - and the unit does have a 1GHz processor & 512 MB RAM.

Unfortunately the DNS-343 brochure does not mention processor or memory, but it does have UPS support, both shutdown & startup.

fordem wrote:

- and the unit does have a 1GHz processor & 512 MB RAM.

I think you are mistaken. The 1GHz processor & 512 MB RAM is what is required on your desktop computer, not the specs of the unit. I imagine it has identical specs as the 323, but it lacks the USB port. There is no mention of using it with a printer so I think the 321 name makes sense. It is a step down from the 323 from what I can see.

fordem wrote:

craft - what's the throughput like in a RAID5 configuration?

I'll test this tomorrow.
Right now I'm testing ext2 vs. ext3 system.


more details :

little change in the housing - horizontal HDD slots (instead of the 323/313 vertical slot(s) )

jumbo frame supported (like in DNS-323 1.05 fw)

Two buttons in the front - "power" and "next" - push power over 5 sec. ->shutdown the device
and push "next" -> next screen in the oled.

haldan wrote:

fordem wrote:

- and the unit does have a 1GHz processor & 512 MB RAM.

I think you are mistaken. The 1GHz processor & 512 MB RAM is what is required on your desktop computer, not the specs of the unit. I imagine it has identical specs as the 323, but it lacks the USB port. There is no mention of using it with a printer so I think the 321 name makes sense. It is a step down from the 323 from what I can see.

You're right - I was looking at a print of the data sheet and the inkjet was streaking at the end of the page - looking at the PDF it's very clear.

craft wrote:

assuncap wrote:

The DNS-321 looks to have IP webcam support, could be a nice low end surveillance solution.
But is that the only difference for the 323?!
A better CPU and more Ram would be nice... and the case looks cool too.
We have to wait for the first reviews.

321 is less than 323 - so I think memory reduced (...32 mb) , minus USB port = low-cost version of the DNS-323

i suspect that is true... it's very sad. Maybe what dlink wants is to compete with Linksys nas200's price tab.
men how i would love 256mb or 128mb on that machine.

I guess we need a dns-324 with oled screen(just to be cool) and 128mb of ram

Last edited by assuncap (2008-06-04 01:31:30)

nULL, you say the DNS-343 has been out in the UK for a while, but I can't find it for sale anywhere. Can you let me know where?

Cheers,
Gareth.

Last edited by gareth (2008-06-05 15:37:58)

performance in raid5, that's what interests me the most too. cpu could be huge bottleneck here

raid6?

no actually, raid6? was the question if raid6 is possible. i do know how raid operates

The datasheet does not mention RAID6 - so depending on the RAID technology used maybe, maybe not.  If it's OS driven RAID, I'm sure someone will find a way to manipulate mdadm and make it happen.

BUT - like RAID0 and JBOD - would there be any advantage?

In addition to the potential for performance degradation mentioned above, RAID6 would require two "drives worth" of storage space reducing the available capacity to 50%

For those not familiar with RAID here are a few nice links.

This one is an HP white paper comparing the perfomance of RAID + ADG (advanced data guarding), HP's name for RAID6, to RAID 0+1

This one is a chart comparing the, so to speak, cost of the different RAID methods - and if you're interested, there is a link to the entire "book" in pdf format in the upper left of the page.

For the record - I have no affiliation with HP/Compaq - I am HP APS certified and I do recognise that many of the innovations in the PC server market place are the result of their research, I was at one point very "pro Compaq" and have always been amused to see technology available on Compaq servers being introduced on Dell & IBM equipment many years later, (I am also Dell DCSE and IBM Business Server Support certified)

Last edited by fordem (2008-06-11 19:03:58)

RAID 0+1 is also not mentioned on the website.

There have been some interesting debates on implementation of RAID 10, 0+1, 1+0 - the definitions of which vary from one manufacturer to another (a mirrored spanned array or a spanned mirrored array), some hardware based implementations dictate which can be used.

Depending on the implementation, the array may not survive the failure of a second disk - and this may also be dictated by the location of the second failure, relative to the first.