dnyberg

There are applications, such as streaming video or seeding torrents, in which reading a file may take hours, even if it's not huge, eg 2 hours to stream a movie file. It seems abusive of the hardware to keep drives spinning for hours or days to source a file. Is there a way, either natively or some sort of plugin or something, to cache files that are being read *from* an unraid server? Even just doing it in RAM would work; RAM's cheap nowdays. Thanks!

Hm, ok, so "emulated drive" is scratch storage used by the rebuild process, and then either handled as described above, or in the more usual situation (we do have a fresh drive to pop in) copied to the replacement drive? What's the physical basis of the emulated drive; is that space borrowed from the surviving healthy drives, or a physically separate drive set up just for that purpose, or...?

Ok, so this influences procedure: Suppose we have an array with a bunch of drives, say 6TB each. Parity drive(s) exist, one data drive fails. Suppose also that no replacement drive is currently available, but the surviving data drives have sufficient empty space, say 10 TB free. Do we absolutely have to have a replacement drive to swap in for the failed one before we regenerate, or can unraid regenerate data and put the recovered data into that existing free 10 TB? The answer to this tells us if we have to have a spare drive on the shelf at all times, or if all available drives can be installed from the beginning. Thanks!

Can anyone explain the difference between exos E series and X series? Poking about their site wasn't illuminating. TIA

Ok, so back to topic: Opinions on family choices for this application (cost and reliability count, speed doesn't)? We don't have to be insane about reliability, as this will be a parity'ed volume. Does anyone know what reputation Arsenal drives have? Never heard of those until recently.

Universal feature now? Ok, cool.

So my intended use for a nas is data hoarding: reads will be rare, writes even more so, speed isn't important (I was happy in the 100mb lan days), reliability matters, server will spend 99.9% of its time completely idle. Back in the day, WD had a green line, the gimmick being the drives powered down when idle. Marketed as energy saving, but one could argue less mechanical wear also. Green series is gone, but surely some drive families exhibit that behavior? So I can do my own shopping, but do people know drive families that meet those goals: reasonable cost, reliability, low spindle speed is fine, and power down is desirable?

Thanks, I understand now.

Okay, I think I understand the system now. Just to confirm, now I have a bunch of 4TBs, and two 6TBs as parity drives. Now I add a 3rd 6 TB, this one set as a data drive. My useful storage has now increased by 6TB?

Ok, let me clarify: assume the 4TB initial build will have 2 of the 4TB drives as parity. So we add two 6TB, make them the parity drives, free up two of the 4TB's for general storage pool. Depending on how the 6TB drives are used, I have gained either 8 or 12 TB of useful space. Which is it, please?"

Suppose I made an unraid with a bunch of 4tb drives. Then later on I add a couple of bigger drives, say 6TB. They'd have to be made into parity drives; I understand the biggest-drive rule there. But I wonder about the utilization of space on these mixed size drives. So let me phrase the question most succinctly: "Do I gain, in this scenario, 8 or 12 TB available storage?" Thanks!

Cute link, thanks for that! It doesn't address my clutter/cabling issue, as he clearly is just going with the traditional Box of Many Cables approach, but it does display ingenuity and a possible direction. Not to mention that he put out the build files for people to use. Again, thanks, though I'm still clinging to hope I can do something pretty similar to what the 45drives bunch offers.

I don't intend to purchase a consumer case, and the enterprise models I see cost a fortune; their main benefit being they provide backplanes to reduce the internal clutter and airflow problems. (I'm impressed by the systems I see on 45drives.com for example, but $4000-$6000 to start isn't going to happen.) Rather, I expect I'll have a friend with cabinetmaker skills build an enclosure to my specs. So I have design flexibility to meet my needs exactly, and it'll be cheaper as well. If I'm stuck running 16 sata data and power cables around (32 cables total!), then I'm stuck doing that, but I'll have to make it a lot larger to accommodate an extra couple of inches behind every drive so the cables don't have to bend too sharply, plus probably more space to accommodate airflow, and all that otherwise useless cabling as well. Backplanes that take a single SAS connector each (8639, I think?) would solve a lot of clutter/airflow issues. I'm hoping that approach is feasible.

So I'm planning a personal NAS server; I can source motherboard, psu, enclosure etc, and gather from this forum a 93xx series controller is the sensible approach. So far so good. But where I'm stuck is in finding backplanes to connect 4, 6 or maybe 8 3.5" sata drives to an 8643 cable. If I had to use those 8643 to 4x sata type cables, it seems to me I'd end up with an enormous mess of cabling snaking about in the enclosure; I'd much rather find backplane cards to reduce that clutter. (I'd kindof like to build with space for 16 drives, and all that cabling adds up.) But everything I'm finding at any reasonable cost online are pulls from proprietary servers. I don't object to used on principle, but the sellers all weasel on the details; they don't say "this card uses X connectors", but rather "this is for your dell this, ibm that, hp something else server". I understand their not wanting to be responsible for compatibility issues, but that's a problem for me. Are there 8643 to satadrive backplanes popular in this group that I could go looking for? It's the last bit I need to find before melting my debit card. Thanks in advance, everyone!