Scalable (> 24 TB) NAS for research department
I have been asked to provide a new fileserver to store our medical images (raw format, not dicom). As we have no IT staff, I have to find a solution, and I hardly know anything about this topic.
The requirements we have are: scalable to 24 TB in 3 years, windows file sharing and the share has to be as big as possible (1x24TB share). First thing I found is the NETGEAR ReadyNAS 3200. Seems like a very good system, accompanied by a big community, which could come in handy if we run into trouble.
But how scalable is this system? Everywhere I'm told that this system is 'not stackable'. I don't know how stacking NAS' work, but maybe we could buy an iSCSI initiator, configure all NAS' as iSCSI targets, then build a raid on the initiator covering all targets, then share this big raid as one windows share? Or can't this be done? I'm clearly at a loss on how scalability works, so if anyone could explain this, I'd be very grateful.
If anyone sees another solution (like another NAS comparable to the readynas'specs but stackable), you can suggest this too of course.
Solution 1:
Stackable means that there is a method to connect more disks to the same NAS controller, usually via SAS or something like that, so you can increase the capacity of the same device.
While the Netgear will be available with a 12x2TB (24GB) configuration shortly, according to their website, I don't think that this system will fit your needs, as you will be left with far less storage when configured properly. Depending on your safety requirement, the capacity of one to three disks will be lost (RAID5 means 1 disk lost, the recommended RAID 6 means 2 are gone and if you use a hotspare, you have only 18TB left).
If you are willing to build a file server 'head' anyway, as suggested with your iSCSI RAID idea, one possible solution would be to either buy a server with 24 or even 48 drive bays and install either Win Server or some Linux variant or a more common 1U pizza box server and a RAID box connected via either iSCSI, SAS or Fibre Channel. This RAID boxes, i.e. from Infortrend, are usually stackable, so you can extend the storage afterwards.
BTW, building a RAID from "cheapish" NAS class iSCSI targets is nothing I would recommend, as your whole raid will be lost if you lose the connection to one of the NAS boxes.
If you are not short on budget, you might consider devices like the NetApp FAS2000 series, which are scalable up to more than 100TB, but still offer CIFS file server functions.
What I really would recommend though is looking for a company specializing in storage applications, which often sell many brands and can advise you on what is best for your specific environment, including the all important backup scenarios ( which is really important to do right).
Solution 2:
The Sun x4540 will support the storage size you need and ZFS makes it easy to share via CIFS for your Windows machines or you can export the storage over iSCSI. However, as other have mentioned, you should really have a plan for backups and redundancy. Since you don't have any IT staff a vendor who will set everything up for you is probably a good choice.