My (somewhat silly) SSD dilemma

July 16, 2014

The world has reached the point where I want to move my home machine from using spinning rust to using SSDs; in fact it's starting to reach the point where sticking on spinning rust seems dowdy and decidedly behind the times. I certainly would like extremely fast IO and no seek overheads and so on, especially when I do crazy things like rebuild Firefox from source on a regular basis. Unfortunately I have a dilemma because of a combination of three things:

  • I insist on mirrored disks for anything I value, for good reason.

  • I want the OS on different physical disks than my data because that makes it much easier to do drastic things like full OS reinstalls (my current system is set up this way).

  • SSDs are not big enough for me to fit all of my data on one SSD (and a bunch of my data is stuff that doesn't need SSD speeds but does need to stay online for good long-term reasons).

(As a hobbyist photographer who shoots in RAW format, the last is probably going to be the case for a long time to come. Photography is capable of eating disk space like popcorn, and it gets worse if you're tempted to get into video too.)

Even if I was willing to accept a non-mirrored system disk (which I'm reluctant to do), satisfying all of this in one machine requires five drives (three SSDs plus two HDs). Six drives would be better. That's a lot of drives to put in one one case and to connect to one motherboard (especially given that an optical drive will require a SATA port these days and yes, I probably still want one).

(I think that relatively small SSDs are now cheap enough that I'd put the OS on SSDs for both speed and lower power. This is contrary to my view two years ago, but times change.)

There are various ways to make all of this fit, such as pushing the optical drive off to an external USB drive and giving up on separate system disk(s), but a good part of my dilemma is that I don't really like any of them. In part it feels like I'm trying to force a system design that is not actually ready yet and what I should be doing is, say, waiting for SSD capacities to go up another factor of two and the prices to drop a bunch more.

(I also suspect that we're going to see more and more mid-tower cases that are primarily designed for 2.5" SSDs, although casual checking suggests that one can get cases that will take a bunch of them even as it stands.)

In short: however tempting SSDs seem, right now it seems like we're in the middle of an incomplete technology transition. However much I'd vaguely like some, I'm probably better off waiting for another year or two or three. How fortunate that this matches my general lethargy about hardware purchases (although there's what happened with my last computer upgrade to make me wonder).

(My impression is that we're actually in the middle of several PC technology transitions. 4K monitors and 'retina' displays seem like another current one, for example, one that I'm quite looking forward to.)


Comments on this page:

PC tech is constantly changing so I'd say there's no point waiting - buy it when you need it. Check out the ASUS Z97-DELUXE if you need lots of SATA ports.

By Edward Berner at 2014-07-17 11:29:36:

Maybe push the storage off of your workstation onto a NAS device? I'm pondering a Dell T320 for that purpose (it has a case option with holds eight 3.5" drives). I currently have a two disk NAS appliance which is convenient but is a little slow and lacks ECC memory.

By mtk@acm.org at 2014-07-17 13:25:45:

i forget what linux dist you use (fedora?). have you looked at building a system around dm-cache? how large could your disk 'working set' be?

By cks at 2014-07-21 17:29:43:

I have two problems with a NAS: I don't trust any commercial ones and I don't have a particularly good place to put another machine. As odd as it sounds for a sysadmin, right now I only have a single machine at home and I like it that way.

I've now taken a look at dm-cache and related things and my gut reaction is that I'm not happy with any of them. What I want is something optional that I can hang off on the side (especially as I have several filesystems that I'd like to accelerate), not something that demands that I completely revise how my disks look so that everything goes through it.

(In short what I want is ZFS L2ARC, where you can attach a L2ARC device to an existing pool, remove it later, and the whole thing is completely transparent. In theory I could get this with ZFS on Linux, but I'm not willing to trust ZFS on Linux anywhere near that far just yet.)

By opk at 2014-08-01 08:32:14:

Mid-tower cases might start coming primarily designed for 2.5" SSDs but I reckon it won't be long before SSDs start coming more and more in a form that resembles RAM chips. If you're short of space in your case, then rather than move the optical drive to external USB, you might even want to consider one of the PCI express cards that allow you to use M.2 or mSATA SSDs. You can also get enclosures for putting multiple 2.5" discs in the 5 1/4" drive bays.

Written on 16 July 2014.
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