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What are the pros and cons of using an SSD as the only drive in a workstation instead of an array of several HDDs or a fast 10k/15k HDD?

To be more specific, Intel X25-M 80GB with Windows 7 x86-64 installed for use in developer/designer workstations, using a NAS, SAN or file server for storage of large files and the SSD for the source code.

Two I can think of right now:

Pros:

  • Cheaper - you don't pay for additional HDDs

Cons

  • Less space - you don't have the space of HDDs
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SSD as opposed to a single HDD? How is that cheaper? Or do you mean an array of HDDs to get the same speed as the SSD? –  HannesFostie Jun 21 '10 at 9:12
    
@HannesFrostie: As opposed to using an array of HDDs. –  Mircea Chirea Jun 21 '10 at 9:36
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7 Answers

up vote 5 down vote accepted

An SSD will dramatically speed up anything that's I/O bound. Examples might include large compiles with lots of files, database work or slinging around large bodies of web content. Generally your punters' user experience on machines with SSDs will be much better.

Currently SSDs are quite expensive compared to consumer level hard drives or even enterprise class 15k RPM disks, but the cost of an X25M is still going to be a small fraction of the overall hardware and software costs of the desktop. If you're comparing it to an array of disks in the machine it may even be cheaper.

80GB is a lot of installed software and most development environments don't involve tens of gigabytes of data. For comparison, I have a development machine with VS, SQL Server, several business intelligence tools including MicroStrategy and quite a bit of other software, which takes about 45GB of disk space in total. The code base and other random files on the disk take about another 10GB(1).

You can manage disk space on an ad-hoc basis. If one of your punters runs out of space you can expand their machine by adding a second disk. SSDs might be prohibitively expensive if you're into HD video editing, genome sequencing or ETL development, but they're not likely to be a major issue otherwise.

NAS and gigabit ethernet are commodity items and make a good 'fast enough' platform for secondary storage unless you are working with large data volumes. Overall, I would expect workstations with SSDs and secondary storage on NAS hardware to perform well for most workloads.

Pros

  • For W7, the I/O latency is dominated by disk head seeks and rotational latency rather than bulk data transfer. A SSD will be dramatically faster on this type of workload than even a large number of disks in a RAID-0.

  • The SSD will be more reliable - no moving parts.

  • An SSD will run fine in a standard case/PSU.

  • For a Windows 7 developer workload I would expect to see SSDs provide by far the best performance. SSDs are already viewed as quite a good way to extend the usable life of a laptop - many models are sold with PATA interfaces for precisely this reason.
    At a guess, I would say that a SSD would expand the lifespan of your computers quite substantially. Given the relative cost of hardware to salaries in Romania, that might be enough to make the business case by itself.

Cons

  • They are somewhat pricey and not very large, but as above 80GB is actually quite a lot of room. Wear levelling is pretty much a solved problem in modern SSDs, so that's a non-issue these days.
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The SSD's price is about 25% of the dev hardware (i5 750, HD 5670, 8GB, lots o' coolers). That's not exactly a small fraction, but it could be well worth it. –  Mircea Chirea Jun 21 '10 at 13:26
    
How much does the software cost? If I had VSTS, a data modelling tool, XMLSpy, Office, Visio, Redgate and a bunch of other stuff on a machine the cost of the software would substantially outweigh the hardware. The software to develop LAMP applications on a Linux based workstation is quite a bit cheaper. In London the cost of a developer's salary would far outweigh both. Salaries are probably somewhat lower in Romania, but I doubt a developer's salary would be so low that the price of a SSD is significant in comparison. –  ConcernedOfTunbridgeWells Jun 21 '10 at 15:06
    
@Concerned, most people here won't get close to several thousand USD a month even in their wildest dreams because of the poor economy (thanks to very high levels of corruption in the government). It is true that the cost of software dwarfs that of hardware, but for a small business saving money is essential. Since you can't easily say "use Linux" (for which lots of technologies are free/cheap) and Microsoft won't cut the price on everything - hardware comes up next. –  Mircea Chirea Jun 21 '10 at 15:14
    
@Concerned, as for "somewhat lower" salaries, the minimum salary here is about USD 200. A salary of $400-500 is common, higher being usually for high-tech and/or experienced people. –  Mircea Chirea Jun 21 '10 at 15:17
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If $500 is a typical developer's salary, a SSD is worth about two weeks. Granted the numbers are bigger in London, but I wouldn't expect to have to jump through too many hoops to get capex signed off for something worth two weeks' salary. Note that the SSDs will probably also expand the usable life of your hardware as well - they would pay for themselves just on the hardware costs if you get an extra year out of the machines. –  ConcernedOfTunbridgeWells Jun 21 '10 at 16:17
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Also take into consideration that most SSDs will run much hotter than even a pair of regular drives when pushed hard - so make sure you have good air clearance capabilities built into your machine (unless you don't intend to push them very hard anyway).

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A solution is to use a cooler for them, or have a case with several good coolers (four 120mm ACs for example). –  Mircea Chirea Jun 21 '10 at 11:51
    
@iconiK, having or adding Four 120mm fans isn't an option in many cases. Most Workstations I've seen have one or two fans, and are usually meant to be quiet. –  Chris S Jun 21 '10 at 13:24
    
120mm fans are pretty quiet. The case is what makes it possible, I don't think you'd need more than two case fans even for high powered components, but since the slots where there, why not? Fans are cheap. –  Mircea Chirea Jun 21 '10 at 15:55
    
I've observed the maximum power consumption for many 2.5" SSD drives are around 2-3 watts. For standard HDD, it's 4-5 watts. While the drive itself may feel warmer, the total heat contribution is a less... hence extra cooling shouldn't be necessary. –  James Schek Jan 5 '11 at 5:00
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As you're comparing an SSD to an array of drives, consider "Single Point of failure" as one of the cons, too.

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RAID 0 could also be considered single point of failure. –  Mircea Chirea Jun 21 '10 at 10:16
    
Absolutely right, iconiK, but I'm assuming - possibly wrongly - that no one would be crazy enough to use RAID 0 for data they cared about. If they are, then the choice between SSD and traditional disks is not their biggest problem. –  RobM Jun 21 '10 at 10:28
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And many of us are considering RAID 0 a non-raid system. –  Pier Jun 21 '10 at 10:30
    
@Robert, The valuable data would sit in a repository or on a NAS/file server and be backed up. It would be OS + temp data. I don't think any sane IT guy would recommend his company to use just RAID 0 for valuable data (unless he hates his company that is). –  Mircea Chirea Jun 21 '10 at 11:49
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@Pier - Technically Raid-0 has no redundant disks - it is an array of inexpensive disks, but not a redundant one. –  ConcernedOfTunbridgeWells Jun 21 '10 at 17:56
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Actually, it is:

Pro: Speed. Lots of it. (If you buy a fast drive.)

Cons: Price. Size. (SSD drives are small).

My workstation has: - One 256 GB SSD drive for system and source code. - Two 1 TB SATA drives connected into RAID0 for video files and other stuff. - One 512 GB SATA drive for onsite backup.

If you can live with a 256 GB, then one SSD would work great for you.

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256GB is very large. Windows 7 x86-64 Professional takes about 10GB on a full install; source code is not that big (it's text!), except maybe if you store a really big SVN repository. –  Mircea Chirea Jun 21 '10 at 9:43
    
Your computer sounds suspiciously like a home computer; not a professional workstation. Though you are correct, pro: speed; con: size. –  Chris S Jun 21 '10 at 13:27
    
@Chris S, what makes you say that? The video card? That's just for a three monitor setup; coolers because the case has the slots and you can never go wrong with more cooling; i5 750 because i7 is much more expensive... and this: xkcd.com/303 –  Mircea Chirea Jun 21 '10 at 14:30
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Don't forget that some SSD's have a limited (compared to a hard drive) number of writes, called "Write Endurance". This article discusses the issue in some depth. It was certainly an issue with older SSD's, but is becoming less of an issue with newer ones.

An SSD might be more suitable for an OS drive that doesn't change that often, whereas a normal hard drive is more suitable for a data drive that's frequently written to.

If you do go with SSD's make sure you find one with a low "Write Endurance".

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I don't think anyone cares about older SSDs anymore; X25-M can handle quite a lot of abuse. –  Mircea Chirea Jun 21 '10 at 10:17
    
All SSDs have a write limit. Use the drive enough and you'll end up with unwritable sectors. Modern SSDs do last a long time, but it's certainly not forever. –  Chris S Jun 21 '10 at 13:28
    
@Chris, of course they won't last forever (and not as long as good HDDs), but by the time they die it's likely much better ones are available. Since they don't hold any valuable data, a dead SSD is not a problem, just an annoyance. –  Mircea Chirea Jun 21 '10 at 15:29
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One possibility could be to use an ssd as a cache for slower media.
Example is using ZFS file system.
Unluckily as far as i know no windows file systems can do that.

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Sure they can. It is called ReadyBoost, and of course it works better with high-end SATA flash drives than with cheap USB flash drives. It doesn't hold a candle to the sophistication of ZFS, but it certainly exists and it is functionally similar to l2arc (but not zil). –  Skyhawk Oct 10 '10 at 15:49
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I seldom see any huge speed improvements using SSD or multiple 10-15krpm raid0 drives for "linking and compiling large builds"... switching to an even faster CPU on the other hand will give a lot more gain.

I'd reserve the SSD for OS and application files instead, this will speed up the user response time in bloated IDEs like Visual Studio by a lot... but adding in a single low-fi 500 GB temp drive would be almost free - code and generators doesn't take much space but, the built binaries and generated intermediates can take a lot of space and modern 7k2rpm SATA drives will handle linking and building just fine.

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