Costly SSDs Worth It, Users Say

Lucas123 writes "When you're paying $30,000 for a PCIe flash card, it had better demonstrate an ROI. While users are still struggling with why solid state storage cost so much, when they target the technology at the right applications, the results can be staggering. For example, when Dan Marbes, a systems engineer at Associated Bank, deployed just three SSDs for his B.I. applications, the flash storage outperformed 60 15,000rpm Fibre Channel disk drives in small-block reads. But when Marbes used the SSDs for large-block random reads and any writes, 'the 60 15K spindles crushed the SSDs,' he said,"

Comments

My approach

[Anrego]

Small (and cheap) 32GB SSD for my desktop...

Big powerful 12TB file server using traditional disks for the bulk of my data.

Performance for the stuff where the SSD makes a difference (program files), cheap storage for the stuff where it doesn't (just about everything else).

And if that 32GB drive dies (unproven technology.. MTBF is still a guess) .. I'll buy another cheap (probably cheaper at that point) one and restore from my daily backup.

Dan "Obvious" Marbes

[demonbug]

For example, when Dan Marbes, a systems engineer at Associated Bank, deployed just three SSDs for his B.I. applications, the flash storage outperformed 60 15,000rpm Fibre Channel disk drives in small-block reads. But when Marbes used the SSDs for large-block random reads and any writes, 'the 60 15K spindles crushed the SSDs,' he said,"

So when you need lots of small, random reads, 3x SSDs beat 60x HDDs. Most of the time is spent seeking the file on the HDDs, your ~4.6 ms random seek time is an order of magnitude or more slower than the flash-based drives. No surprise here.

When you are just transferring large files, most of the time is spent actually transferring data. A modern SSD might manage 300-400 MB/s read, but 20x as many HDDs are still going to beat the crap out of them.

The only mildly surprising part is that part about the HDDs winning for all writes, but I guess that really depends on how the test is set up - unless you are actually writing to random parts of the HDD, it is basically a straight-up write operation, so only throughput matters - and again, 60x HDDs are going to beat 3x SSDs (though it is important to note that SSDs are significantly slower at writing than reading in general, although still much faster than an HDD on an individual basis).

Re:And still no SSD caching for Linux file systems

[TheInternetGuy]

No, you are supposed to start a flame-war on lkml about how SSD cache is a stupid idea that will never amount to anything. Next hundreds of kernel developers will start develop the code to prove you wrong.