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Can SSDs Be Used For Software Development?
hackingbear writes "I'm considering buying a current-generation SSD to replace my external hard disk drive for use in my day-to-day software development, especially to boost the IDE's performance. Size is not a great concern: 120GB is enough for me. Price is not much of a concern either, as my boss will pay. I do have concerns on the limitations of write cycles as well as write speeds. As I understand, the current SSDs overcome it by heuristically placing the writes randomly. That would be good enough for regular users, but in software development, one may have to update 10-30% of the source files from Subversion and recompile the whole project, several times a day. I wonder how SSDs will do in this usage pattern. What's your experience developing on SSDs?"
If you're worried about losing work, I think your backup solution is what you need to improve instead.
The main difference is a good SSD is much, much faster than any hard drive. If discussions about the topic don't give that impression, it's only because people fixate on sustained transfer - where there is still some competition between slower SSDs and hard drives - rather than seek time, which is often more important, and where SSDs blow the doors off hard drives. To me, suddenly widening the biggest bottleneck in PC performance for the first time in a couple decades is pretty exciting.
Cheaper drives (which mgmt is sure to require) have 1,000 write cycles (assuming the worst). For certain high-traffic files, that means (assuming 30 writes in a day) a whole 33 days of use.
If that were true. Then an SSD hard drive couldn't run a linux mail server for a small business for more than a couple minutes thanks to the various log files.
1) The maximum write cycles for a block was around 10,000 in 1994. And about 100,000 in 1997. But in 2009 you think 1000? No. Its currently in the millions, even for the cheap SSDs.
2) Look up wear levelling.
3) Look up the MTBF on an SSD vs a spinning platters type.
I've seen studies that have calculated that modern drives will could write continuously at maximum speed for 50+ years before exhausting wear levelling and hitting write cycle limits.
The odds of it failing from something else long before then are much greater. Getting a mere 5+ years of life and easily beating your average spinning disk hard drive is a no brainer.
NTFS has a fairly high overhead for a compile, lots of small temp files that all have to be created and deleted having their ACL's added to the MFT and then removed. I've seen compile time drop to 1/4th the time by switching from NTFS to FAT32 on the same hardware.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
That way it'll encourage them to write efficient implementations.
Actually, the opposite is true.
If development is painful (which it is, if your workflow is hampered by slow builds), you will produce crappier code. It's all about retaining focus & flow. Sad thing is, compilation still takes too long; you can still check your gmail or refresh slashdot.
How many of you are reading this article while automake is checking the version of your fortran compiler in order to run gcc on a .c file?
Save your wrists today - switch to Dvorak
The whole "millions" thing may be true for SLC parts. MLC parts (which are much cheaper) have much lower write counts. The best MLC flash I'm aware of is only rated for a million write cycles. Thousands or tens of thousands is more typical for MLC flash parts. Write amplification makes this even more fun, since it means that a write of one disk block can require rewriting many, many blocks that otherwise would not have been written. If the wear leveling algorithm is optimal, then it's a moot point. If the wear leveling is nowhere near optimal, you can create artificial workloads that will burn out a few cells on the flash part in hours, which is a bit problematic. There is no clear-cut answer for this sort of question, unfortunately, at least not with the current crop of MLC tech.
Consider a log-structured filesystem, perhaps....
Check out my sci-fi/humor trilogy at PatriotsBooks.
If you build is really IOPS-bound, then an SSD will utterly smoke a single disk. Even a whopping great expensive disk can only muster 300 iops under the best possible circumstances, and typically 100 iops under real conditions. A cheapo SSD can deliver 1000 mixed iops, and a good SSD can deliver 100,000 mixed iops. Ever since switching to an SSD on my dev machine I no longer have to suffer through things like a :wq in vim taking 5-10 seconds, or loading a file taking several seconds, etc. One of the benchmarks I did was starting Firefox during a build. On the machine with a disk, it actually took more than ONE MINUTE to start Firefox under a build load. With the SSD, there is no measurable difference between the Firefox startup on an idle machine and a machine with a build happening. The difference is massive.