On Sun, 24 Jan 2021, John Jason Jordan wrote:
I have a Mediasonic 2-bay enclosure with a 6TB and an 8TB WD red. I set them up as RAID0, which resulted in a volume of 12TB because RAID0 gives you (number of drives) * (the size of the smallest drive).
John, That's what I learned today when I refreshed my minimal RAID knowledge.
If I had it to do over again JBOD might have been a better choice because it would not have wasted 2TB of space. The drives were backed up nightly to a NAS as a mirror, so I didn't need redundancy within the Mediasonic.
Yep, JBOD is readily handed by LVM2. I'll partition/format (ext4) the four physical disks, make a physical group, then set up one or two logical volumes.
My Mediasonic has connectors for USB 3 and eSATA, and the computer that I connected it to had both of those ports as well.
I suspect all their enclosures have both interfaces.
There isn't a lot of difference between the two connectors as to speed, and I didn't have an eSATA cable, so I used USB.
Interesting. I've read that eSATA is faster (same speed as internally mounted drives), but it also depends on what else is on the USB.
After a couple years the USB port on the Mediasonic got flaky, so I bought an eSATA cable. I didn't notice any difference. But eventually I called Mediasonic and for $20 they sold me a new PC card with both connectors, only about 2cm square. It was trivial to open the case, and replace the old card. I mention this just so you know that I had good service from Mediasonic.
I read that SATA is more reliable over the long term so I bought a Mediatronic PCIe card with two external SATA ports ($23) and a 2m/6' SATA-eSATA cable. The Asus motherboards on my desktops have 6 SATA headers so running one of them to the back of the case for external drives makes life easier.
If you want the drives in the Mediasonic to look like just one big drive, then your choices are RAID0 or JBOD. If you want two drives of your four to be one big drive mirrored to the other two, so you have redundancy within the Mediasonic, then I think you can make each pair RAID0 or JBOD, and then both of these volumes can be made into a RAID1 (but I've never done that, and I'm sure someone here will tell me that I'm wrong. But bear in mind that RAID0 is a bit faster on read/write than JBOD. Whenever I tell professionals who work on big data centers that I use RAID0 they immediately tell me what a bad idea it is because if either drive fails then you've lost the whole thing. But they don't realize that my RAID0 arrays are backed up nightly to a mirror on my network, so I do have redundancy, just not the way they are used to doing things.
I have a 2Tb external hard drive that stores daily (well, nightly really) differences in changed files. I don't keep backups for long; dailies for a month, weekly (Sunday) files for 6 months. I've never needed to go back more than a couple of months to restore I file I really needed. (Except the one time a hard drive failed on me and Keith told me just how to do a Dirvish bare-metal restore. Then I was back in business again. So JBOD using LVM2 will do what I need.
The Mediasonic and its drives are now about four years old so, although they are working fine, it was about 75% full, and I replaced it with a new Thunderbolt 3 enclosure that has four 7.68TB U.2 drives, also set up as a RAID0. (Fast!) The new setup lost its RAID array a few days ago and it looks like I'm going to have to recreate it. I'm still trying to figure out what caused the failure - right now it looks like TB3 on Linux is disconnecting the drives every 15 seconds, and this is a recent development because it was working fine for several weeks. In the meantime, since the middle of December, the Mediasonic has been sitting here unplugged.
They are good units. Thanks for sharing your insights with me, John. Stay well, Rich _______________________________________________ PLUG: https://pdxlinux.org PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
