On 4/5/2014 8:13 AM, David Boreham wrote:
On 4/4/2014 5:29 PM, Lists wrote:
So, spend the money and get the enterprise class SSDs. They have come
down considerably in price over the last year or so. Although on
paper the Intel Enterprise SSDs tend to trail the performance numbers
of the leading consumer drives, they have wear characteristics that
mean you can trust them as much as you can any other drive for years,
and they still leave spinning rust far, far behind.
Another issue to bear in mind is that SSD performance may not be
consistent over time. This is because the software on the drive that
manages where data lives in the NAND chips has to perform operations
similar to garbage collection. Drive performance may slowly decrease
over the lifetime of the drive, or worse : Consumer drives may be
designed such that this GC-like activity is expected to take place
"when the drive is idle", which it may well be for much of the time,
in a laptop. However, in a server subject to a constant load, there
may never be "idle time". As a result the drive may all of a sudden
decide to stop processing host I/O operations while it reshuffles its
blocks. Enterprise drives are designed to address this problem and are
specified for longevity under a constant high workload. Performance is
similarly specified over worst-case lifetime conditions (which could
explain why consumer drives appear to be faster, at least initially).
My experience has been, consumer SSDs used in a high usage desktop type
environment are about twice as slow after a year as they were brand
new. I note my current desktop system has written 15TB total onto my
250GB drive after about 16 months. The SMART wear leveling count
suggests the drive has 91% of its useful life left.
--
john r pierce 37N 122W
somewhere on the middle of the left coast
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