This document applies directly to the Hewlett Packard Proliant DL185 G5 server. I have tested this with the twelve front bay configuration and will test shortly with the rear-facing drive configuration as well. [Edit – Tested with fourteen drive configuration and it checked out just fine.]
When buying a hot-swap SAS or SATA 3.5″ hard drive for use in your new HP Proliant DL185 G5 you can acquire them directly from HP with the drive carrier (or sled, caddy) already attached. This is the easiest method. If you are like me and prefer to select your own drives from third party makers (in my case, I want to use low power, high capacity Seagate Barracuda LP drives) then you must purchase your hot swap drive sleds separately. Finding the correct part number from HP can be quite a hassle. Even calling them for support can be tricky as almost no one buys this part directly.
If you wish to get your drive trays separately and not through HP you may be in tough shape. HP does not stock this part and, in fact, is unable to even look up this part number for you. I spent some time working with HP in the US on this issue and they were able to provide a visual confirmation on the part for me but could not verify the quality or the usability of the third party drives that I was able to find. So I was stuck taking a risk to see if these drives would work. For some machines HP can provide a part number and sometimes can even sell the caddy themselves, but not in the case of the 185 G5. I have taken the time both with HP and with the third party vendors and with the server in-hand to verify these parts so you do not have to do so.
The part that you need to purchase is HP Part Number: 373211-001. This part is generally priced around $35 USD. You will need as many as fourteen of them to fully populate the DL185 G5 drive with the two optional large drive bays (twelve in front and two in back) but you can use them individually as well, or course. I have had good luck and have gotten a good price getting these trays from Discount Technology: DL185 G5 Hot Swap Drive Tray.
Beware of shops attempting to sell you a much lower cost alternative to this part number. Quite often the lower cost part is actually a drive blank. A drive blank is simply a plastic air dam that corrects airflow through the server chassis when a drive is not present. Many of these drive blanks should ship with your DL185 G5 when it is new. They are readily available and very inexpensive but, mostly, useless.
The big advantage of working with third party sleds and drives is that the DL185 G5 can be populated for thousands of dollars less and can house as much as 28TB of storage in a tiny 2U server. This is possibly the second densest storage unit on the market when used with the Seagate Barracude LP 2TB drives – the densest is the Sun x4500 “Thumper” 4U storage server at many times the cost of the DL185.
Also, when ordering a DL185 G5 you should be aware that if you get the larger twelve hard drive front drive bay that you cannot also have a front loading optical drive and will need to get your optical drive rear facing. If you get the optional dual hot swap rear facing drive option then you cannot have a rear facing optical drive. If you choose both of these options you must use a USB-based optical drive in order to boot from optical media. This is not always obvious when you are attempting to order one of these machines.