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I've been tasked with specing out upgrading our backup process. Right now we have a DAT72 drive that's been used for the last 3 or 4 years and can hold 6 tapes. Now we'd like to simplify the process so we don't have to keep changing out tapes every other day now that we can use 3+ for a backup.

We're using the latest version of Backup Exec and would like to use a hard drive based solution for daily incrementals along with the weekly full and also use the tapes for an archival copy of the full.

Would a standard SATAII 7200rpm drive work okay for this or should I be looking into something more like SAS/SAS2? How many drives would be recommended for this and in what configuration?

jldugger
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Brian Surowiec
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6 Answers6

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I suggest 2TB drives in RAID 1. If you need speed, upgrade to the 32MB Cache and RAID 0+1.

tsilb
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    In most situations, especially on a backup server, 1+0 is preferred to 0+1 as it can sustain more drive failures in certain situations and rebuild times for a failed drive are significantly faster. – MDMarra Aug 11 '09 at 01:55
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How large and frequent are your backup? Generally for backup, you can get away with using SATA drives as performance isn't that important. You may want to look into starting with a HP MSA shelf directly attached to a server. That would let you use either SAS or SATA drives. I would also recommend at least RAID 5, if not RAID 0 with one or more hot spares, but then I'm paranoid about data loss.

GardenMWM
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    Don't you mean RAID 10 or RAID 1? AFAIK, RAID 0 doesn't use hot spares, and is generally considered to be a ticking timebomb to most admins anyway, since it's not redundant. – Ernie Aug 10 '09 at 23:45
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    I'm inclined to believe he meant 10, not 0. At least I hope so. – MDMarra Aug 11 '09 at 01:51
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    Yep, definitely meant RAID 10. RAID 0 would not be a good thing for backups, unless you worked for Enron. – GardenMWM Aug 11 '09 at 16:50
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For a while I used our old mostly decomissioned no longer on support SAN. It had something like 3T of raw space in 15k RPM SCSI drives. I could push them pretty much to the limits with NetBackup using it as a disk target for backups. We just had RAID5 run across each shelf of disk so we could get some redundancy but mostly speed.

It depends on how many streams of data you want to push at once. Also once my data started expiring and we were re-writing things eventually slowed down a ton due to fragmentation, even across 40+ disks.

Currently I'm using a VTL for my disk backups, and I've had far fewer problems with performance loss due to fragmentation. This is because it partitions the disk into "tapes" that then get recycled into big chunks of free space when they expire.

How many drives and what size you get depends largely on your data set. How much do you back up in incremental backups weekly? How many weeks do you want to hold? Multiply. How big are your full backups? How many do you want to hold? Multiply and add to the first value. Now consider how fast your data set grows, over estimate some. How long do you plan on using this solution before you upgrade again? Add up the previous numbers and multiply them by your data growth rate over time. That should be a good start at your sizing.

Laura Thomas
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The more, the merrier. Use RAID6, so you can suffer two drive failures.

David Pashley
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Ack, I hate tapes. If you don't require a lot of archival stuff, I would look into getting a Drobo Pro + some kind of online backup ( Dropbox, CrashPlan, JungleDisk etc. ). The Drobo is dead simple, just add sata drives, and it will auto expand / protect your data.

user16227
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If you're not absolutely committed to disk, I may be so bold as to suggest an alternative...

LTO is cheap these days (especially considering the amount of storage you can get on them) and even a single slot LTO4 drive will have ample capacity for your requirements. You say you're using 3+ tapes per backup and changing all 6 every other day? That indicates to me that a single LTO4 tape should hold a full weeks backup for you (compressed), thereby eliminating your major headache of tape changing. Worst case - allowing for double future growth - you're looking at changing a single tape twice per week. Use a small tape library and you've got even less changing to do.

Performance-wise the limiting feature is going to be your bandwidth - LTO4 is fast as well.

What this will give you is 1.6 TB (compressed) per tape, at a cost that no disk based solution is going to be capable of comparing with, while at the same time retaining most of the flexibility of a disk-based solution. The extra advantage is that - because it's so cheap per GB - you're in a position where you can hold much much more historical data. Plus it's going to be more reliable and robust than disk.

Maximus Minimus
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  • I actually think this is my best option in terms of daily, weekly and archival backups and was my first choice when the DAT72 setup was purchased. And as much as I’d love to do it now there’s no way I’d get the funding still. – Brian Surowiec Aug 16 '09 at 06:03
  • I say this very embarrassed, but I was first handed a 1TB WD USB drive and told to use that for our backups now (even told I should use the software it comes with so we don’t have to upgrade Backup Exec). It took a while for them to get that I can’t run backups that way and that we need to use something better. It’s shocking to see some people hate their data this much to not care about how it’s saved. – Brian Surowiec Aug 16 '09 at 06:04