Post by seasoned_geek Post by Stephen Hoffman
And if still on HDDs while pondering permuting preferred path, promote
pondering SSDs too. FC SAN Storage Controllers are fast, but HDDs are
HDDs and slow and there's only so much cache.
In the PC world that hasn't exactly been my experience. SSDs are very
fast with READ operations but duth sucketh with WRITE operations. They
mask this with cache. When you are doing massive write operations, you
need a spinning disk.
...and several different Samsung 840 series SSDs the build time
difference was about an hour...
If this was ~five years ago or so, and/or with under-revision storage...
Samsung 840 Pro purportedly had a firmware TRIM bug in then-common
firmware versions. Asynchronous TRIM would delete random data. Linux
worked around that corruption by disabling asynchronous TRIM. Which'd
throttle write performance, causing the observed write behavior.
Samsung released firmware fixes for 840 Pro, 850 Pro, and other
effected devices some years ago.
Among various discussions of this firmware bug from back then:
Post by seasoned_geek
Some day I will experiment with a hybrid drive.
Unimpressed with the Apple Fusion hybrid drives; HDDs with a
variable-size flash cache. The performance is better than HDD on
average, though apps can end up running at HDD speeds if (or when?) the
Smaller caching best needs to be cognizant of system and app activity
(XFC, etc), where simpler caching further down the I/O hardware stack
can't be and can trade off cache sizing (hopefully) for performance
increases. All designs have trade-offs and compromises.
With contemporaneous server and app and storage designs and with
contemporaneous pricing, HDDs tend to best be used for archival
storage. When you need big pools of storage, and aren't in a hurry to
access it; fast nearline, or backup, or archival storage.
DVD, HDD, and other storage firmware has also had issues. There were
well-known-vendor-branded optical drives that sometimes mis-recorded
data, as verified with OpenVMS and a patched DQDRIVER. And OpenVMS
itself has shipped with firmware maintenance tools for updating storage
There's the whole discussion of how VSI OpenVMS will be auditing
firmware and how customers will be loading new vendor firmware with the
OpenVMS x86-64 port, too. Firmware is ubiquitous, residing within
processors, management processors, storage, NICs, and ~everything else.
Server maintenance starts out problematic, and the mess increases as
the numbers of servers in use increases.
The OpenVMS servers configured with SSD storage are stonking fast, and
the configurations have been at least as stable and reliable as HDDs.
And did I mention stonking fast I/O?
Pure Personal Opinion | HoffmanLabs LLC