68 PCWorld MARCH 2020REVIEWS SAMSUNG PORTABLE SSD T7 TOUCH
you’d think the T7
outperformed the T5 by a
mile. While it’s reading or
writing to cache, it does.
Off-cache it’s a bit slower.
The SSD creates cache by
treating some of the
NAND as SLC (generally)
by writing only 1 bit—a
much quicker operation
than writing the 3 bits TLC
is capable of storing, and
especially the 4 bits QLC
can store.
Our test 500GB model
had around 20GB of cache, so we expect that
the 1TB will have 40GB of cache, and the
2TB, 80GB. Samsung and most vendors have
historically assigned cache by percentage,
but we didn’t have the larger-capacity drives
to check that theory on the T7. There are
smart cache allotment controllers out there
that will increase cache according to need,
but from the behavior, it doesn’t seem as if
the T7 is one of them.
According to CrystalDiskMark 6, the T7
is megafast. With very small amounts of
data that’s true, but in real-world copies, its
reading and writing is about half what CDM
6 (and AS SSD—not shown) show. What can
we say?
Once the T7 dropped out of cache, it
wrote about 50MBps slower than the older
T5, which maintains long writes at 350MBpsto 375MBps. That deficit slowly catches up
with the drive as the amount of data being
written increases, so it actually turned in
slower 48GB and 450GB write results than
the T5. If you write only to the cache, the T7
tops 500MBps and is much faster. That’s likely
99 percent of the time for most users.
The T5 (350MBps) is actually a bit faster
writing once the T7 runs out of cache
(300MBps). With our 500GB T7, that was at
roughly the halfway mark in the 48GB write
test, allowing the T5 to catch up. The 1GB T7
would likely have posted better numbers in
this test.
The 450GB copy shown below is a test
we use to reveal cache dropouts with larger-
capacity drives, which may allot more cache
than the 48GB we’re limited to writing from
our 50GB RAM disk. It can also illustrateSequential W(Q =32, T=1) riteSequential Read
(Q =32, T=1)CrystalDiskMark 6
(MBps)507925
511LONGER BARS INDICATE BETTER PERFORMANCESandisk Extreme Portable SSDSamsung T7 Samsung T55421,034
561According to CrystalDiskMark 6, the T7 is megafast. With very small
amounts of data it is, but in real-world copies, it’s not nearly this fast.