/tech/ - Technology★

>>1062424 (OP)

fugg meant to post that in the questions thread

jim fix noscript-posting

>>1062424 (OP)

>And is HDD in a laptop acceptable?

Yes, but a SSD is better for portable devices. In fact, HDDs are superior to SSDs in most ways.

>>1062427

Agreed, but I'd never put an HDD in a laptop if I had the choice. They're just not meant to be moved around like that.

>Does mirroring zfs over HDD and SSD make sense?

No, zfs makes no guarantees about where the data is coming from, it won't prefer the SSD over the HDD for reads.

What you can do instead of using this meme is use lvm + ext4. You can lvm mirror two partitions, one on the hdd, one on the ssd, and then assign one a "write-mostly" flag.

--[raid]writemostly PV[:t|n|y]
              Mark a device in a RAID1 LV as write-mostly.  All reads to
              these drives will be avoided unless absolutely necessary. This
              keeps the number of I/Os to the drive to a minimum. The
              default behavior is to set the write-mostly attribute for the
              specified PV.  It is also possible to remove the write-mostly
              flag by adding the suffix :n at the end of the PV name, or to
              toggle the value with the suffix :t. Repeat this option to
              change the attribute on multiple PVs.

http://man7.org/linux/man-pages/man8/lvchange.8.html

>>1062424 (OP)

Are you talking about having an ssd and hdd in the same vdev or pool? If so, DON'T do that. ZFS is not built for this in mind and won't do anything special. You'll have the worst space and performances limitations of boths disks, and none of the benefits.

If you are talking about using an SSD based pool for active work, and using an HDD pool to send snapshots for a backup, then that's both fine and recommended.

If you are asking about using mirrors over raidz2/raidz3, then:

-For IOPs, mirrors are usually significantly better than raidz levels, especially once you hit 3 vdevs in a pool. A single SSD will always be vastly superior to HDDs in regards to IOPs.

-For throughput, it really depends.

-The biggest downside of mirrors is space needed for parity. Mirrors don't make sense for large storage pools. Put data that is written once and occasionally read on a raidz2-3 pool.

-Mirrors are easy to expand with only two disks needed. Great for people starting out with storage.

>>1062797

>ZFS

>Great for people starting out with storage.

https://github.com/zfsonlinux/zfs/issues?q=panic

Doesn't ZFS allow adding an SSD to a pool as a cache disk?

When will these stupid captchas go away?