I've added the two OnStream drives (ADR50 and SC30) in the internal
SCSI configurations (wide connector if available). I've listed the
pricing I can get to keep the comparison prices consistent.
Steve Rothman, the Eliant 820 is an Exabyte drive utilizing an 8mm
helical scan tape. The VXA-1 media $/GB price is also actually a bit
higher than you calculated
Media
$/GB
---------------------------------------------------
Exabyte M2: 60GB, 12MB/s, $3777 ($80 media) 1.33
Sony AIT-2: 50GB, 6MB/s, $3289 ($94 media) 1.88
DLT 8000 : 40GB, 6MB/s, $3915 ($64 media) 1.60
Sony AIT-1: 35GB, 3MB/s, $1913 ($88 media) 2.51
VXA-1 : 33GB, 3MB/s, $939 ($67 media) 2.03
ADR50 : 25GB, 2MB/s, $697 ($46 media) 1.84
DDS-4 : 20GB, 3MB/s, $1072 ($33 media) 1.65
Mammoth : 20GB, 3MB/s, $2126 ($56 media) 2.80
DLT 4000 : 20GB, 1.5MB/s, $1352 ($64 media) 3.20
SC30 : 15GB, 2MB/S, $438 ($41 media) 2.73
Mammoth-LT: 14GB, 2MB/s, $1193 ($35 media) 2.50
DDS-3 : 12GB, 1MB/s, $777 ($16 media) 1.33
Eliant 820: 7GB, 1MB/s, $1160 ( $8 media) 1.14
DDS-2 : 4GB, .51MB/s, $606 ( $7 media) 1.75
-Native capacity listed, compressed capacity is typically 50% more
-Sustained transfer rate listed
-Cost is based on internal model with wide SCSI connector (if available)
-VXA-1 tape drive is even cheaper through Ecrix July promo ($539)
-Media listed is highest capacity format in single packs
Here's how I personally chose which tape drive to go with:
The way I figure, in order, the most important factors regarding the
tape backup system are:
1. Reliability
2. Performance
3. Ease
4. Cost
Some of these items will be in different order for other people but I
think that reliability is always the most important factor in a
backup. (To stress my point, substitute the word "parachute" for
"backup." I'm sure you'll always choose the most reliable parachute
over any other.)
Reliability: The key feature with a backup is the ability to restore
data and no tape system is 100% problem-free. But, only Ecrix makes
these ridiculous durability claims and actually backs it up with
extreme torture tests (boiling & freezing tapes). This is what really
got my attention on the VXA drives.
Performance: You need to backup your users in the shortest amount of
time possible. If it takes you more than one night to create a full
backup, some users will go more than a day between backups thus
reducing your backup system's effectiveness. Plus, the less you
inconvenience your users, the less likely they'll keep "snoozing"
Retrospect when it starts a backup. But with a fast tape drive you'll
need a fast network and fast clients. Watch for the bottleneck.
Ease: higher capacity tapes reduce the amount of tape swapping that
needs to happen during a backup or restore. If it takes 5 tapes to
perform a full backup, then it'll take 5 nights before the full
backup is done and the first incremental backup can take place
meaning that some people will go 5 days between their full and
incremental backups. Ideally, a full backup will fit on a single tape
or you'll have an autoloader.
Cost: lower = good but when computing the cost per GB, you must
factor in the cost of the tape drive as well. $7 media sounds really
appealing but weigh in drive cost, performance and storage capacity.
Below, I've computed actual cost per GB for my test scenario of 100GB
total to backup, 3 storage sets.
Tran #Tapes Total True
Model (GB) Rate Price Media Req'd Price $/GB
-----------------------------------------------------------
VXA-1 33 3MB/s $539 $67 12 $1,343 $3.39
DDS-3 12 1MB/s $777 $16 27 $1,209 $3.73
DDS-2 4 .51MB/s $606 $7 75 $1,131 $3.77
SC30 15 2MB/s $438 $41 21 $1,299 $4.12
ADR50 25 2MB/s $697 $46 12 $1,249 $4.16
VXA-1 33 3MB/s $939 $67 12 $1,743 $4.40
Eliant 820 7 1MB/s $1,160 $8 45 $1,520 $4.83
DDS-4 20 3MB/s $1,072 $33 15 $1,567 $5.22
Mammoth-LT 14 2MB/s $1,193 $35 24 $2,033 $6.05
DLT 4000 20 1.5MB/s $1,352 $64 15 $2,312 $7.71
Sony AIT-1 35 3MB/s $1,913 $88 9 $2,705 $8.59
Mammoth 20 3MB/s $2,126 $56 15 $2,966 $9.89
Exabyte M2 60 12MB/s $3,777 $80 6 $4,257 $11.83
DLT 8000 40 6MB/s $3,915 $64 9 $4,491 $12.48
Sony AIT-2 50 6MB/s $3,289 $94 6 $3,853 $12.84
For this comparison, I've included the VXA-1 at the promotional price
since it's been extended through Aug and is available to everyone.
The total cost of DDS-3 is actually $134 cheaper than the VXA-1 but
the cost/GB is higher, it requires 27 tapes total (9 tapes per
storage set) and its transfer rate is considerably slower.
So, it's probably fairly obvious that I went with the VXA-1 drive.
The promo price was so good that I bought two. This gives me a
pseudo-autoloader and also gives me redundancy in case one drive
fails. Am I concerned about the new-ness of the drive? Of course. I'd
prefer that there were multiple manufacturers and multiple media
sources. But, with the way hard drive capacity/usage is increasing,
I'll likely be in the market for a new drive after a couple of years.
At 8:03 PM -0600 8/2/00, Douglas B. McKay wrote:
>May I add one other drive to this list? What does anyone here think of this
>drive from OnStream (http://www.onstream.com)? Other than having a few
>(three in one machine), I have no connection to OnStream. They seem to work
>well, I just hadn't seen much mention here in the time I've been lurking...
>
> ...Doug
>OnStream
>ADR50 : 25GB, 2MB/s, $700 ($50 media)
>
>Exabyte M2: 60GB, 12MB/s, $3777 ($80 media)
>Sony AIT-2: 50GB, 6MB/s, $3289 ($94 media)
>DLT 8000 : 40GB, 6MB/s, $3915 ($64 media)
>Sony AIT-1: 35GB, 3MB/s, $1913 ($88 media)
>VXA-1 : 33GB, 3MB/s, $939 ($67 media)
>DDS-4 : 20GB, 3MB/s, $1072 ($33 media)
>Mammoth : 20GB, 3MB/s, $2126 ($56 media)
>DLT 4000 : 20GB, 1.5MB/s, $1352 ($64 media)
>Mammoth-LT: 14GB, 2MB/s, $1193 ($35 media)
>DDS-3 : 12GB, 1MB/s, $777 ($16 media)
>Eliant 820: 7GB, 1MB/s, $1160 ( $8 media)
>DDS-2 : 4GB, .51MB/s, $606 ( $7 media)
>
>-Native capacity listed, compressed capacity is typically 50% more
>-Sustained transfer rate listed
>-Cost is based on internal model with wide SCSI connector (if available)
>
>-VXA-1 tape drive is even cheaper through Ecrix July promo ($539)
>-Media listed is highest capacity format in single packs
>-----------------------------------------------
>
>
>
>
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