I'm currently planning to revamp a "computer". Using the term "computer" because I'm not sure what it's role exactly is...
It runs Ubuntu (17.10 / artful), it's being used as multi-seat desktop for two users, it stores about 1.5 TB of data (documents, images, music), it serves as media center and nfs4 server and it runs two libvirt virtual machines, serving as local webserver, mail server and mysql database server.
Backup runs every night, but I didn't want to rely on the disk drive to be kind enough to fail immediately after backup and before any file changes, so it currently has two ext4 formatted 2TB disks in a software (md) raid-1.
I would like to take advantage of the performance of SSD drives, but currently two high-quality 2TB SSD are a bit beyond my financial possibilities...
This leads me to think about SSD/HDD hybrid drives (also referred to as SSHD), where SSD cache provides high performance for new and frequently used files, while old and seldomly accessed files reside only on the slower spinning disk.
Also, I'd like to move over to BTRFS because I'm appealed by it's snapshot and built-in raid support.
As far as I can say, BTRFS distinguishes between SSD and HDD (i.e. spinning and solid state disks). Which should I chose? I suppose that it would rather be spinning disk because in this special case BTFRS should not try to apply any special precautions as the drive's firmware is specifically designed to hide the fact that there is an SSD part involved from the file system driver.
If not BTRFS, then even with other file systems like ext4, is combining two SSHD in a software raid-1 generally a good idea?
I'd also be glad if you can give some hints or reading recommendations on how to implement a SSD cache myself, where for example files not accessed during the last month would transparently be moved to a less expensive storage medium.
Thanks in advance,
Patrick
