Build Flexible Expandable NAS for SOHO use

Hi,

I have been looking into the possibility of building a NAS for SOHO use.

Examining all the various prebuilt products on the market, most of these are not really suitable having limited expandability (limited to trays in cabinet), limited features (Premium cost for features such as iSCSI), and exceedingly expensive with minimal features. I am less interested in the "Home" Features though I will use the NAS to store AV, I would make space from the NAS accessible to other machines for storing and playback of such media.

Another option of building a NAS based on a home computer is by itself inadequate as it will be limited to the motherboard connections, and I could not use Intel Matrix RAID aka Fake RAID as this is only supported with windows and I intend to use Linux. I also would not be happy to use Linux Software RAID as Software RAID while more portable is less reliable and significantly more complicated to setup and maintain in such a way as to allow for fault tolerance and hot swapping of the media. Expandability is also an issue given the limit of 6 ports.

Most people might think that 6 hard drives would be more than adequate and this may be true, however I intend to set up a NAS with 3-4 groups of disk. Each Group will grow with time, I will start off with 1 Group, and every 6-12 months will add/or upgrade a Group. So perhaps I will organise the array in the following manner:

Period Group Description
1 1 3x1.0TB RAID 5 2TB
2 2 3x1.5TB RAID 5 3TB
3 3 5x1.5TB RAID 5 6TB
4 1 5x2.0TB RAID 5 8TB
5 2 8x2.0TB RAID 6 12TB
6 3 8x1.5TB RAID 6 9TB
7 1 5x2.5TB RAID 5 10TB
and so on.

The content of a Group to be upgraded would be transferred onto one of the other Groups, and one Group would always provide backup for the other two in case of multiple disk failures in addition to using Standalone Disks for Offline backup. I would use inexpensive high capacity disks since the NAS would not be running 24/7 but on demand, and where possible smaller older disks would be recycled into larger arrays.

I am therefor forced to look for a hardware RAID solution.

One of the preferred solutions is Adaptec's recent RAID 5xxx Series cards.

I understand that even the more basic Cards can support up to 128 Disks by using SFF-8087/88 Cable and Daisy Chained Enclosures.

It would be my preference to build a small energy efficient PC equiped with 2-4 Gigabit Ports and 1 basic Adaptec RAID 5xxx series card with a maximum of 2 internal ports and an adapter to convert internal to external. I would then also like and prefer to buy small free standing NAS cases with Internal SAS hotswap bays holding 5 drives in 3x5.25" Bays and using 1 or 2 per NAS Case.

The idea is that these NAS Cases so equiped, can be bought as needed over time in order to expand the storage potential of the NAS.

I do not need to buy additional controllers except perhaps to have a backup Controller in case the primary controller fails.

I do not want to have a Rackmountable 1/2/4/8u enclosure, I am not interested in buying or having an enclosure and do not really want to have this type of enclosure standalone either.

My problems is that I can find the "Internal SAS hotswap bays holding 5 drives in 3x5.25" Bays" however most of these that I have located are not capable of daisy chaining as the Rackmounted variety are.

This means I would be forced to either buy an incredibly expensive high end RAID card for additional ports allowing and limiting me to 4 drives per SFF-8087/88 port or a rather unappealing and expensive Rackmountable enclosure.

I am not so concerned about performance, each SFF-8087/88 port supports a Full-Duplex Bandwidth of 24GBit/s so having up to around 36 (100MBit/s) drives on one port should not create a bottleneck, though I would likely split the drives over multiple ports where possible.

I am relatively new to this technology though I am reasonably experienced with computers and technology. My ultimate objective is to create a (relatively) inexpensive but very expandable solution.

I estimate that I would spend around £250 on the computer, around £300 on the RAID Controller, around £125 for case and empty enclosure per 5 disks and disks would cost between £50 and £75 each depending on capacity and age of technology (I would wait for prices to drop and the latest generation of disks to be superceeded, before buying). While this initial cost may be quite high (around £1000), the cost to expand would be substantially smaller versus the cost to buy prebuilt NAS.

Does anyone know where I can find a suitable "Internal SAS hotswap bays holding 5 drives in 3x5.25" Bays" and any other parts that might be useful?

Thankyou in advance for any assistance you can provide.