ssd for /home

Przemysław Orzechowski przemek.orzechowski at makolab.pl
Thu Oct 16 17:45:44 UTC 2014


On 16.10.2014 18:24, Luciano Gabriel Andino wrote:
> Hi, I am thinking to change sata disk for /home and I want to know if
> change to a SSD hd, is a good option. I have 30-40 accounts with 30-50K
> email in boxes.
>
Hi

SSD's give you fast read and (degrading with time) fast write 
performance but at a cost.

Even server grade SSD's are prone to sudden failures. Mostly due to 
exeeded max write count. And when they fail you lose whole data stored 
on them (this happened fiew times in my work) So we are using SSD's as 
fast storage ie as cache, but always have a persistent copy somwhere 
else or store data that can be easily reconstructed in case of SSD's fail.

You can read SSD disks all the time but writing to them causes fast 
wear. Most SSD's have a specific limit of numer of writes (more specific 
erase cycles for memory blocks) and when they reach that limit they just 
stop working.
In mirror raid both drives will fail almost at the same time, couse of 
identical workloads.

Thats what my experiences with SSD storage is.
The other factor is the price.

In my laptop (not so heavily used - fiew VM's and ubuntu desktop (30% of 
the drive left unpartitioned) an intel consumer grade SSD died in a year 
(no files recoverable).

So my advice is either store dovecot indexes on SSD (should improve 
performance) or have a mirror (dsync ?) of Your /home on some other 
(magnetic) storage unless You are ok with the loss of /home contents


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