I have been testing an internal SATA RDX drive, made by Quantum, in an IBM x-series 226 server with dual 3.0 Ghz CPU's, 3 GB of RAM, and dual 73 GB SCSI drives configured as a simple RAID 1. The Operating System is Red Hat Enterprise Linux 5.3, Microlite BackupEDGE version 03.00.03 with the RDX cartridge configured as a file system partition. I modified the retention time to be only 3 days, as I was backing up to the same cartridge, and wanted to verify that the program would automatically delete the oldest archive to make room. When we have a cartridge for each workday, I will extend that back out to 2 weeks.
Backup performance : SUMMARY - BACKUP Serial Number = demo1011 Date = Tue Nov 22 01:04:12 2011 Files Encountered = 288530 Total Data = 31.60GB Data Written = 31.87GB Volume Left = 114.53MB Segments Used = 32 Elapsed Time = 00:34:04 Data Transfer Speed = 93.838 GB/hr = 1601.513 MB/min = 27988485 bytes/sec Exit Status = 0 Verification : SUMMARY - BYTE-BY-BYTE VERIFICATION Serial Number = demo1011 Date = Tue Nov 22 01:40:13 2011 Segments Used = 32 Data Read = 31.88GB Elapsed Time = 00:35:58 Data Transfer Speed = 54.419 GB/hr = 928.756 MB/min = 16231202 bytes/sec Files Encountered = 288530 Files Excluded = 4 Files Modified = 7 Files Not Checked = 2 Special Files = 21031 Verified Successfully = 267488 Change Log = /usr/lib/edge/lists/simple_job//changedfiles_system_mas ter.txt Status = No problems found Exit Status = 0
The time to backup on our current Iomega REV internal SCSI drive, with a similar amount of data, was 36:52, and the verify was 36:25. Admittedly, the current backup happens when the system has live user activity, but the users can really notice the slowdown when the backup/verify is active. I did login to the test system while the backup was running to the RDX drive, and it did not seem to slow down as much. This was probably due to the SATA connection being separate from the SCSI backplane for the RDX drive, whereas the Iomega REV is also a SCSI device. Setting up the RDX cartridge as a SharpDrive device was slightly slower, somewhere between 1 and 2 minutes slower overall.
Where the RDX drive really shines though, is on a Selective Restore. In essence, the RDX cartridge is a hard drive, so the access time for individual files is extremely fast. I restored one of our largest files (782 MB) :
SUMMARY - RESTORE Serial Number = demo1011 Date = Thu Nov 03 16:08:53 2011 Elapsed Time = 00:00:40 Data Transfer Speed = 109.793 GB/hr = 1875.469 MB/min = 32776199 bytes/sec Segments Used = 10 Data Read = 782.69MB Files Restored = 1 Exit Status = 0
Forty seconds is excellent. The same restore from our REV drive took over 28 minutes.
Performance aside, the fact that Iomega no longer makes the REV drives is what is making this decision for me. Also, the cost per Gigabyte on the cartridges is extremely low (320 GB for $112.75), and we are not limited to a cartridge capacity going forward. It will also be nice to have multiple week's worth of data on each cartridge. If a user was to mess up one of their files, and not realize it for a week or two, we would have them covered.
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