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New PCIe SSDs Load Games, Apps As Fast As Old SATA Drives
crookedvulture writes Slashdot has covered a bunch of new PCI Express SSDs over the past month, and for good reason. The latest crop offers much higher sequential and random I/O rates than predecessors based on old-school Serial ATA interfaces. They're also compatible with new protocols, like NVM Express, which reduce overhead and improve scaling under demanding loads. As one might expect, these new PCIe drives destroy the competition in targeted benchmarks, hitting top speeds several times faster than even the best SATA SSDs can muster. The thing is, PCIe SSDs don't load games or common application data any faster than current incumbents—or even consumer-grade SSDs from five years ago. That's very different from the initial transition from mechanical to solid-state storage, where load times improved noticeably for just about everything. Servers and workstations can no doubt take advantage of the extra oomph that PCIe SSDs provide, but desktop users may struggle to find scenarios where PCIe SSDs offer palpable performance improvements over even budget-oriented SATA drives.
Most folks who need the throughput of a PCI-E SSD won't use it for just gaming. These same users are likely power users. Everything from running test VMs locally to Video / Audio editing would see a huge improvement from this tech.
Loading apps? games? That's nice and all, but those are far from the only use cases of fast storage media.
Personally, the new PCI-E SSDs have gotten a good amount of use from me as ZFS cache drives, where they've been wonderful for saturating 10gbps Ethernet.
I have an x25-m G2 80GB and a crucial M500. The crucial drive has substantially better random iops, and the system does feel faster booting off it than the x25-m. But the difference in "feel" is like a 7200rpm platter drive vs a 10,000rpm platter drive... same ballpark but the 10k is just a bit snappier.
Newer SSDs are definitely faster than earlier ones, but we've kind of hit a wall with needs for even more speed. The slowest (non-broken) SSD you can buy today will be no less beneficial in real world home-user operation than the fastest SSD you can buy. Its just that there is a little bit of room for improvement over 2008-2009 era SSDs. (Don't take this as a disagreement, just an elaboration).
That's isn't correct. The queue depth for a normal AHCI controller is 31 (assuming 1 tag is reserved for error handling). It only takes a queue depth of 2 or 3 for maximum linear throughput.
Also, most operating systems are doing read-ahead for the program. Even if a program is requesting data from a file in small 4K read() chunks, the OS itself is doing read-ahead with multiple tags and likely much larger 16K-64K chunks. That's assuming the data hasn't been cached in ram yet.
For writing, the OS is buffering the data and issuing the writes asynchronously so writing is not usually a bottleneck unless a vast amount of data is being shoved out.
-Matt