On 01/27/2015 11:20 AM, Yasha Karant wrote:
There are hybrid disk drives that have a "small" SSD flash memory along with
the regular spinning media, typically to serve as a cache for lower latency. Does anyone
have long term experience with these units? Most flash memory is not designed for the
long term repeated read/write/erase cycles of a primary disk drive -- how are these
holding up? Is the flash configuration totally transparent to the Linux file systems and
formatting operations?
Yasha Karant
Disclaimer: Since I work for the US Fed Gov, I am not endorsing or disapproving
any products, just sharing my experience.
My experience with the Seagate 2TB's ST2000DX001 is they're getting SMART warnings of pending/offline
sectors in a typical desktop setting after just a few months of 24/7 use, where other drives have lived
for years. My last failure locked up the Dell BIOS and the system wouldn't boot unless you hit F12 to
boot the other drive. I think I've only deployed about five drives and at least three are in the
'dead' pile already. Reviews weren't bad when I bought, but it's pretty ugly now with 25% out of 200
being 1-egg ratings:
http://www.newegg.com/Product/Product.aspx?Item=N82E16822178380&SortField=0&SummaryType=0&PageSize=10&SelectedRating=-1&VideoOnlyMark=False&IsFeedbackTab=true#scrollFullInfo
I don't think the SSD is to blame, it's the mechanicals.
Again, I use them as replacements a RAID1 configuration, and sadly, haven't
really done much in the way of benchmarking them, but I suspect if you reboot
the system a few times, the boot times will come down, but agreed, as
mentioned, 8GB of SSD (mostly read) cache doesn't help much unless your
read/write patterns are fairly restricted.
What I have found that *does* work well is RAID1 mirroring with SSD and a traditional
"spinning rust" hard drive and using mdadm to mark the partitions on the HD as
"--write-mostly" (fail the devices, remove them, then re-add them with --write-mostly).
You get speed, redundancy, and low cost.
As I manage roughly 170 systems, most desktops which have space for two drives, I cannot
emphasize how nice it is to not have a system go down due to a common drive failure. I
get to replace them on a schedule that works best for me and the user, not when they're
screaming "I'm dead in the water!"
