On 6/01/2010 7:19 AM, Richard Elling wrote:
If you are doing small, random reads on dozens of TB of data, then you've
got a much bigger problem on your hands... kinda like counting grains of
sand on the beach during low tide :-). Hopefully, you do not have to
randomly
update that data because your file system isn't COW :-). Fortunately,
most
workloads are not of that size and scope.
Since there are already 1 TB SSDs on the market, the only thing
keeping the
HDD market alive is the low $/TB. Moore's Law predicts that cost
advantage
will pass. SSDs are already the low $/IOPS winners.
-- richard
These workloads (small random reads over huge datasets) might be getting
more common in some environments - because it seems to be what you get
when you consolidate virtual machine storage.
We've got a moderately large number of Virtual Machines (a mix of
Debian, Win2K Win2K3) running a very large set of applications, and our
reads are all over the place! :-( I have to say I remain impressed at
how well the ARC behaves, but even then our hit rate is often not
wonderful.
I _dream_ about being able to afford to build out my entire storage from
cheap/large SSD's. My guess would be that in about 2 years I'll be able
to. One of the reasons we've essentially put a hold on buying
"enterprise storage" or fast FC/SCSI disks. A large part of the
justification for FC/SCSI disks is their performance, and they're going
to be completely eclipsed within the lifetime of any serious mid-range
to high end storage array. Until that day we're make do large sata
drives, mirrored, with relatively high spindle counts to avoid long
per-disk queues.
:-)
T
PS: OK, I know other tier-1 storage vendors have started integrating
SSD's as well, but they hadn't when we started out current round of
storage upgrades, and I stilll think opensolaris+sata hdds+ssd's gives
us a cleaner,cheaper and easier upgrade path than most tier-1 vendors
can provide.
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