Over a period of three weeks, I experienced six complete failures of LTO-1 and LTO-2 tape drives at client sites. Some had failed mechanisms. Others lost the ability to write reliably. These were HP Ultrium 232, 448 and 460 drives. Most of these units were deployed between 2006 and 2008, so the timing of the failures is right. The capacities (400GB) are correct for the applications. I replaced a couple of drives with equivalent devices, just for consistency. One server also had a SCSI HBA failure, further delaying recovery. At that point, the customer asked if there were any hard disk solutions available that would be better (or less-finicky) than tape.
As I began to look for replacements, I discovered that the RDX removable disk storage technology has been adopted by the major server manufacturers (HP, Dell, IBM). From my perspective, it looks like docked 2.5" SATA disks connected either internally or externally via USB2 in capacities up-to 1TB. Since these are actual disks, it seems like recovery and seek time would be reasonable. But I have a few questions about the technology in practice.
- Does anyone here use these drives with success? Is there anything to watch out for?
- What differentiates RDX from straight external USB disks?
- One of the advantages to tape in my application is that the drives have hardware compression. This helps immensely for the highly-compressive datasets I have to backup on Linux systems. Am I correct in assuming RDX relies on software compression?
- Since these are physical disks, are there any mountpoint issues in Linux or Windows? One of the nice things about tape is that its not a mounted filesystem and typically isn't affected by viruses, rootkits, system crashes, etc.
- In addition, I watched a primer on using RDX with Cactus Lone-Tar, and cringed when I saw them using a
mkfscommand to create a filesystem on the RDX drive at
/dev/sda. Is there any chance of device renaming/reordering (from adding a SCSI controller, inserting a USB key, etc.), or will the docking unit persist at a particular device name as you swap drives?
- Are the backup speeds of 30 megabytes/second accurate?
I'm curious, as this could be an interesting alternative. The series of tape drive failures came at a time where it makes sense to reevaluate other options before moving forward.