Re: Home Directory in SSD

Am Sonntag, 7. Februar 2016, 00:57:24 CET schrieb Matus UHLAR - fantomas:
> On 06.02.16 19:30, Jos Collin wrote:
> >I have Debian/testing installed completely in my 120GB SSD. I have
> >learned that if an SSD fails, it is difficult to recover data from
> >them. An SSD often does not give much warning before it fails.
> >Electronic components don’t begin to grind or buzz as they grow
> >older. They work – and then they don’t.
> >
> >So do I have to consider this risk and move the /home and /root
> >directories to an HDD as they contain the Personal Data of each user,
> >and only keep the Operating System files in the SSD ? How do you
> >people keep the /home and /root directories, when you install the OS
> >in an SSD ? (I have an Ultrabay Caddy, in which I can connect the HDD
> >also in my Thinkpad T61).
> 
> this is debian-laptop list, are you really talking about a laptop?
> 
> I consider two possibilities for my home PC
> 1. mirror SSD and HDD (I currently have two old 120 HDDs in mirror)

I think this can be done with regular rsync or btrfs send/receive.

I probably wouldn´t try to use BTRFS RAID 1 or SoftRAID 1, cause I think the 
slower disk will slow down write accesses. Also I am not sure whether the RAID 
implementations are aware of disk speed and for example shuffle most of the 
reads to the SSD in that case. I bet they aren´t (yet).

> 2. using bcache, dm-cache or flashcache (cache HDD on SSD)

If you use bcache with write caching you basically double your risk of data 
loss.

> maybe someone could share experience with some of these...

bcache worked in a test more than a year ago I think. But I don´t use it, so… 
no idea about long term reliability.

And alternative is also using a hybrid harddisk that uses a little amount of 
flash as caching. You have one device and its all transparent. But you have 
lots of logic in firmware. Seagate does these, I am not sure whether other 
vendors do these meanwhile as well.

Personally I only stuff flash into laptops anymore cause laptop is just much 
more silent this way. I didn´t think back then that at one time I´d consider 
even a 2,5 inch harddisk as loud, but compared to the SSD – which can make 
some noices on heavy write accesses, at least my Intel SSD 320 does – they 
are.

Thanks,
-- 
Martin