Note that some RAID controllers (3Ware in particular) refuse to
recognize the MLC drives, in particular, they act as if the OCZ Vertex
series do not exist when connected.
I don't know what they're looking for (perhaps some indication that
actual rotation is happening?) but this is a potential problem.... make
sure your adapter can talk to these things!
BTW I have done some benchmarking with Postgresql against these drives
and they are SMOKING fast.
I was thinking about ARECA 1320 with 2GB memory + BBU. Unfortunately, I
cannot find information about using ARECA cards with SSD drives. I'm
also not sure how they would work together. I guess the RAID cards are
optimized for conventional disks. They read/write data in bigger blocks
and they optimize the order of reading/writing for physical cylinders. I
know for sure that this particular areca card has an Intel dual core IO
processor and its own embedded operating system. I guess it could be
tuned for SSD drives, but I don't know how.
I was hoping that with a RAID 6 setup, write speed (which is slower for
cheaper flash based SSD drives) would dramatically increase, because
information written simultaneously to 10 drives. With very small block
size, it would probably be true. But... what if the RAID card uses
bigger block sizes, and - say - I want to update much smaller blocks in
the database?
My other option is to buy two SLC SSD drives and use RAID1. It would
cost about the same, but has less redundancy and less capacity. Which is
the faster? 8-10 MLC disks in RAID 6 with a good caching controller, or
two SLC disks in RAID1?
Thanks,
Laszlo
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