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The limited writings and capacity\price of the SSD are known drawbacks as the sensitivity to shocks of the HDD.
The hybrid SSHD (standard HDD+SSD cache) have a classic HD combined with a small SSD used as cache and managed by the firmware of the SSHD.
Now I want to know what happens when the SSD cache reaches the writing limit quote for all the cells, the two possible alternatives are:
a) simply the firmware stop to use the SSD caching and the SSHD becomes a standard HDD
b) the SSHD becomes unusable
What is the right answer? (The b alternative would make the SSHD choice, the less durable alternative and the worst choice ever for a server.)
I have searched reliable sources about this, but I haven't found anything.
The mechanical problems of HDD are very rare if they they are not subjected to shocks during the read\write operations, in standard condition the MTF range between 1 million to 1.5 million hours for a modern HDD. In the SSD, particularly SSD TLC, wearing is a problem, MLC typical maximum PE-cycle-per-block numbers range from 1500 to 10,000 (5000 mostly). Reach 5000 cycles is relatively easy if the storage is used intensively (especially in server use). So It's really important the SSD cache durability, and in addition must be considered also that cache-SSD sectors in SSHD are used even most intensively of a standard SSD that can distribute the wearing on a larger space.
1I've never had a modern hard drive fail on me without some extenuating circumstance (i.e. shock to the drive or something) -- but I bought two SSHDs about a year ago (Seagate), and one of them, with only standard usage (no shocks, etc.) has failed already. :( -- I'm thinking ISRT with regular drives is the way to go. – BrainSlugs83 – 2015-09-12T08:09:22.103
1@BrainSlugs83 Could you tell what exactly happened to your broken SSHD? (If bad sector, power issue or whatever else) – Silverstorm – 2015-09-12T22:57:48.253
Should probably point out that this will probably never happen, due firstly to the algorithms in use, and secondly because the cache in an SSHD uses different type of memory to that of SSDs which has hundreds of times higher lifespan - i.e. SLC or high endurance MLC. – qasdfdsaq – 2015-10-16T19:07:41.697