> Do you have any real-life stats about SSD breakage (lifetime > expectancy) in L2ARC usage modes - did any of your SSDs > already reach their end-of-life, and if yes - what percentage > and how old were they? What model(s) do you use?
The oldest round of gear uses 128GB Crucial M4s. I have seen two failures on the M4s and neither was due to cell wear. The first failure was infant mortality with spontaneous failure to complete writes. The second failure had an electrical issue on the bus. Typical l2arc wear on my databases is 10% on each L2ARC device after ten months of operation or at present 7061 power on hours. I use three devices or more per pool. My L2ARC exceeds the size of the live data set in all cases. There are hundreds (and going to thousands) of databases running in zones. My database I/O patterns are write heavy with a large batch job which runs essentially back to back. I have l2arc_noprefetch set to zero which in theory would wear the l2arc devices faster. I have found it to be the right call as it improved the l2arc hit cache ratio significantly for my i/o pattern. My monitoring system uses cacti, zabbix, and graphite. The write i/o requirements are much more intense as a data pool than l2arc on the databases. At this moment, I am at 40% utilization on each of the SSDS for roughly the same time period (7599 power on hours). The warranty on the devices is three years. It is clear the monitoring system is going to burn through the disks before the warranty runs up. By the time l2arc disks wear out on the databases I will be off of them, off the spinning rust, and on to Intel 910s or similar devices. I haven't had enough failures to have any meaningful statistics. j.
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