[plug] musing on HDD types

[Brad Campbell]

On 26/4/21 1:38 pm, William Kenworthy wrote:
> 
> On 26/4/21 1:25 pm, Brad Campbell wrote:
>> On 24/4/21 10:31 pm, Benjamin wrote:
>>> don't go surveillance.
>>
>> Why not?
>>
> They are mostly CMR and relatively slow rpm but are optimised for
> writing streaming data with little read optimisation - very specific
> workload that is not suited to a chunkservers requirements (64Mb chunks
> requiring multiple read random access after writing once.

Surveillance systems do not present a nice neat "streaming write", "read rarely" load. They hammer the disks in both read and write scenarios, and operators do not like to be kept waiting while the system waits for a chunk of data. Even the consumer grade Chinese DVRs are increasingly random after the first couple of passes through the drive as footage is aged out.

The only disadvantage to surveillance drives is they tend to have their power-saving patched out.

Brad
-- 
An expert is a person who has found out by his own painful
experience all the mistakes that one can make in a very
narrow field. - Niels Bohr