On Tue, Jan 19, 2016 at 11:11:22PM +0000, James Harper wrote:
> (it seems that "reply-all" no longer includes luv-main (from ms
> outlook at least), so I have to include it manually... what's with
> that?)
who knows? outlook is weird.
for list replies, it's better to just reply to the list without CC-ing
everyone anyway. i don't care much either way (i have procmail and i'm
not afraid to use it :), but some people really dislike getting dupes.
> > Of course a RAID-1 of SSDs will massively outperform the RAID-5 you
> > have.
>
> If you use SSDs for any sort of intensive storage, do keep an eye on
> the SMART "media wearout" values, and replace them before the counter
> hits 0 (or 1).
the only related value i can find on 'smartctl -a' on my 256GB OCZ
Vertex is:
233 Remaining_Lifetime_Perc 0x0000 067 067 000 Old_age Offline
- 67
I assume that means I´ve used up about 1/3rd of its expected life. Not
bad, considering i've been running it for 500 days total so far:
9 Power_On_Hours 0x0000 100 100 000 Old_age Offline
- 12005
12005 hours is 500 days. or 1.3 years.
and over that time, i've read 17.4TB and written 11.9TB. on a 256GB
SSD...equivalent to rewriting the entire drive 46 times. or approx 23GB
of writes per day.
198 Host_Reads_GiB 0x0000 100 100 000 Old_age Offline
- 17440
199 Host_Writes_GiB 0x0000 100 100 000 Old_age Offline
- 11901
I can expect probably another 2.5 years from this SSD or so at my
current/historical usage rates. by that time, i'll be more than ready to
replace it with a bigger, faster, and cheaper M.2 SSD.
and that's for an OCZ Vertex, one of the last decent drives OCZ made
before they started producing crap and went bust (and subsequently got
bought by Toshiba, who are now producing decent drives again under the
OCZ brand name).....so relatively old technology compared to modern
SSDs.
I'd expect a modern Intel or Samsung (or OCZ) to have an even longer
lifespan.
according to
http://www.anandtech.com/show/8239/update-on-samsung-850-pro-endurance-vnand-die-size
the 256GB Samsung 850 Pro has an expected lifespan of 70 years with
20GB/day writes or 14 years with 100GB/day writes.
The 512GB model doubles that and the 1TB quadruple it.
even if you distrust the published specs and regard them as marketing
dept. lies, and discount them by 50% or even 75%, you're still looking
at long lives for modern SSDs....more than long enough to last until the
next upgrade cycle for your servers.
So, yes, keep an eye on the "Remaining_Lifetime_Percentage" or "Wear
Level Count" or whatever the SMART attribute is called on your
particular SSD, but there's no need to worry too much about it unless
you're writing 1TB/day or so (and even then it should last around 3.5
years).
> I'm seeing time-to-replacement of about 12 months on high load
> system where the SSD's are used for a RAID cache (ZFS, Intel RAID
> controllers, etc).
12 months? how much are you writing to those things each day?
BTW, my OCZs are partitioned and used for OS and /home and ZFS L2ARC and
ZFS ZIL.
i would consider usage to be fairly light, not heavy. the heaviest usage
it suffers would be compiling stuff and the regular upgrades of debian
sid.
> Not particularly relevant to the discussion at hand, but with
> suggestions of "put in SSD's and all your trouble will go away", it is
> something you need to consider.
The endurance issues that SSDs suffered in the past are basically gone
now.
craig
--
craig sanders <[email protected]>
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