Backup device

[SQLScholar]

Hey all,

I am looking for a new tape drive - it must be at least 250gb of storage.

What is proving difficult - is there such a device, which is connected directly onto Gigabit ethernet? See at the moment we are connecting a backup drive through a terrible server (with SLOW SCSI), and even when thats sorted and we have fast SCSI its still only 320mbps.

Any ideas guys/gals?

Dan

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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr. Seuss
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[LWComputingMVP]

I think we may need a better explanation of your network.

I've never seen a tape drive that connects directly to the network. There are drives and devices to connect directly to the SAN.

Now, The fastest SCSI is about 2.5 Gb. Because the SCSI speeds are measured in MBytes, not Mbits. Further, if you do the math on throughput, the fastest tape drive supports a transfer rate of 576 GB/hr, which translates into 160 Mbits/sec (see:

http://h18006.www1.hp.com/products/storageworks/ultrium960/specs.html

)

Now, you need to remember that throughput is NEVER going to reach advertised levels on a consistant basis. For any technology. Backup speed depends on a variety of factors, including size of the files and number of files backed up.

If you provide more information, you can give a clearer picture and we can better tell you what you can expect in your environment.

Lastly, for an understanding of backup in general, you might want to read over my backup comment - it started as a comment on another site and grew and grew and grew, so I made it a web page. See:

http://www.lwcomputing.com/tips/static/backup.asp

 

[SQLScholar]

Ok - I will start from Day 1.

We originally brought a certance carrosel unit (6*dds4) along with a whole package of servers and installation from a third party (this is before i had much of a say, and much knowledge of anything!)

They could never get the backup device to connect to our main IBM servers (x-series) - including aparently speaking to IBM and certance. There work around was to give us a server, to connect the backup unit too. The backup was slow but worked. Now fastforward to today.

The backups are so slow, and the communication to the drive so lax we are running well into the next day to get the backup to complete (usually around 3pm). I have found this is mostly to do with the SCSI card they installed into it, which from what i can tell runs at 40mbps. Now we are going to soon install a new card - but we do have one other issue looming.

We are now backing up onto 5 tapes for a full backup. At this rate sometime next year will probably be 6, and later next year early next we will be out of space.

So to cut to the chase, my question was to find the resolve to both the above, and i was thinking that gig ethernet system (if available) would free up this server AND sort out the above issues.

Any advice greatly recieved, and i will give it to the network guy. Its not generally my line of work, but i am trying to help out.

Thanks

Dan

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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr. Seuss
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[LWComputingMVP]

Here's a few points. The SLOWEST SCSI connection developed runs at 40 Mbits/sec (5 MBytes/sec). This was standardized in the 80's. Todays SCSI connections - and the one you're probably using - is at least 40 MBytes/sec (that's 320 Mbits or more than 3x the speed of a 100 Mbit network). Most SCSI devices sold as new today operate AT LEAST at Ultra160 speeds - which is 1.28 Gigabits (160 MB/sec). So the fact that you're using SCSI is NOT your problem.

Next, I have used a bunch of different SCSI equipment and tape drives, DDS drives, DLT drives, and SDLT drives. I have TWICE experienced EXTREMELY slow throughput (about 40-55 MB/minute speeds that BOTH TIMES turned out to be a SCSI DRIVER issue. On one occasion, it was only solved with a complete reinstall (after a reformat). In both cases, it was using Adaptec SCSI cards. So if that's what you have, I'd suggest replacing them with another brand as that will CLEARLY demonstrate the driver issue.

Then you have to factor in WHAT you are backing up. The types and sizes of files will have a SIGNIFICANT impact on backup speed. Your backups WILL crawl if your backing up 100 GB worth of 50K or less Word Documents. Your backups will fly if your backing two 100 GB of ISO images of CDs that range in size from 100 MB to 4 GB. For LARGE files, using SDLT drives, I've seen performance hit 10 MB/sec - 600 MBytes/min) - which is the general top speed of a 100 Mbit network.

Now, it's VERY unlikely you are seeing 2:1 compression which those tapes advertise. You're probably seeing 1.3:1 or MAYBE 1.5:1 at best. so that means you're backing up 150 GB of data for a full backup. In my opinion - as my web page suggests - using tape is generally NOT THE BEST SOLUTION. Get yourself some external hard drives and backup to those - they are faster and more cost effective. An External USB hard drive will typically max out at about 160 Mbit/sec - or about 900 MB/min.

Lastly, if you really want to solve this problem you need to learn to use performance monitor to review your resource utilization. Track down WHERE the bottleneck is. Arbitrarily replacing components is a great way to waste money and time and NOT solve the problem. (Though from your description, I'd put 2:1 odds your problem is with the controller drivers).

I strongly recommend you read my backup link above - it describes some of these issues in greater detail.

 

[SQLScholar]

Thanks for that - one last question

[/quote]
Get yourself some external hard drives and backup to those -they are faster and more cost effective.

Only problem is currently we have 2 weeks worth of tapes, and 12 for monthly backups. So to get the same granularity (incase of hd/tape failure) we would have to get at least 5 harddisks.

Dan

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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr. Seuss
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[LWComputingMVP]

So? That's $750. A new tape drive that supports a larger capacity tape will cost AT LEAST as much. And then you'll need new media.

 

[wayneta]

lwcomuting is probably right, but to answer your original question, LTO2 has a native capacity of 200 GB which is pretty close to what you are looking for. With compression, my backups approach between 205-249 GB per tape. I don't have any direct experience with DDS4, but LTO2 definitely runs circles around DDS3 as far as throughput.
You'll also get better throughput with 1 gb NICs (over 100 mb NICs).
As far as an ethernet tape drive, are you looking for a NAS or an iSCSI tape drive?

-Wayne

 

[SQLScholar]

I am not quite sure what a "iSCSI tape drive" exactly is (what does the "i" stand for?) but considering we have a NAS already, i presume its what we require.

Thanks

Dan

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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr. Seuss
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