Despite all the hype surrounding disk-based data backup and recovery technology, tape storage remains the primary target for most backups. Tapes not only store the most data, but also most data will be stored directly on tapes during the backup process, without using disks as cache.
After understanding this, we should think about how to make the tape drive have better performance?
1. Get to know your tape drive
The most important aspect of achieving good tape performance is understanding the tape drives you are using in your backup process. Most modern tape drives are streaming tape drives, which means they are designed to transfer data at a certain rate, so in order for a tape drive to work properly, you must know its rate and maintain it during backup and restore. flow state.
So, the first thing we need to do is learn about all the tape drives in use. The first thing you need to know is the tape drive’s maximum raw (uncompressed) transfer rate. For example, the maximum raw (uncompressed) transfer rate of an LTO-4 tape drive is 120MB per second.
Once you know this number, you must determine what the minimum rate of the drive is. This may require some research, but the numbers are certainly documented. If this data is not in the documentation, you will need to contact the manufacturer of the tape drive.
For example, the minimum transfer rate for LTO-4 is about 23MBps to 25MBps. That is, the write rate for LTO-4 cannot be lower than 23MBps to 25MBps. If its actual write rate appears to be lower than this value, the drive is actually The board was writing data in short bursts of 23MBps to 25MBps, then after a short pause it was writing again in short bursts of 23MBps to 25MBps.
You should also be aware of any step rates between the maximum and minimum speeds, on multispeed tape drives like LTO-4 there are usually two to three intermediate speeds between the minimum and maximum speeds. Again, understanding this requires some research, and the answer may well be in the documentation. Once you know these numbers, you should strive for the maximum transfer rate, and anything less than the minimum transfer rate will only get you into trouble.
2. Understand the data transfer rate and compression rate
When it comes to sources, you need to know two things: data transfer rate and compression ratio. You need to know the data transfer rate of different servers. Higher-end servers with higher-end storage tend to serve data at a higher rate than lower-end servers.
You need to be aware of these different data transfer rates when designing your own backup architecture. You can only determine this data through testing. For example, if you know that a particular customer’s database can only transfer data at 10MBps to 20MBps, connecting it to Fiber Channel won’t do anything to increase backup speeds because its speeds are limited to begin with. .
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The next thing you need to know is the rate of data compression. Some data will be compressed at a higher rate than others, and data from different companies will have different compression rates. You need to find out the compression capabilities of the data in your environment.
The reason for this is because you have to multiply the compression ratio with the minimum and maximum transfer rates mentioned above to arrive at the new minimum and maximum transfer rates. For example, if your environment has a compression ratio of 1.5:1, your 120 MBps tape drive becomes a 180 MBps tape drive.
Compression can be determined by looking at the data loaded before the physical end of tape (PEOT) label is reached and the software indicates that the tape is full. If you can consistently write 1200 GB of data into a nominal 800 GB tape, with a compression ratio of 1.5:1, you can multiply the raw throughput by that number.
3. Understand your data path
Once you understand where your data comes from and where it’s going, you also need to understand its route to get there. Will the data go over Ethernet? Is the network Gigabit, 10 Gigabit, or 100 Mb? If your client is capable of transferring data at hundreds of MBps and it’s trying to send its data over a 100 Mb network, what do you get It can’t be very fast. However, such a client is ideal if you are migrating to a LAN-free backup process connected to Fiber Channel.
4. Know your backup application
Knowing this part is a no-brainer, but backup applications can be complex when it comes to performance tuning. Understanding all aspects of the backup product’s performance allows you to “do whatever you want” in actual work.
For example, if you are using IBM Tivoli Storage Manager and are not familiar with array groups, you should carefully understand this aspect. Likewise, if you’re using Symantec NetBackup, EMC NetWorker, and CommVault, and their reuse features,
you should do your homework. You can join a mailing list, forum, or newsgroup and learn how others are making your application perform better. You can also search the BackupCentral.com forums for the keyword “performance” to see what other users have asked and answered on this topic.
5. Understand your disk sales
It has become increasingly difficult to get tape drives to work properly without sending the backup data to disk first. If you’ve recently purchased a tape drive and it didn’t come with disks, you might as well cancel the order and order some disks instead. Believe it or not, moving data twice (backed up to disk and then copied to tape) is much faster than moving it once alone.
Q1: Why is tape storage still the primary choice
Tape storage remains the primary choice for backups because it can store large amounts of data efficiently and most data can be directly stored on tapes during the backup process without the need for disks as cache.
Q2: How can I achieve better performance with my tape drive?
To improve tape drive performance, you should start by understanding your tape drives, including their maximum raw transfer rates and minimum rates. Then, strive to maintain a transfer rate close to the maximum rate during backup and restore operations.
Q3: What are streaming tape drives
Streaming tape drives are designed to transfer data at a constant rate. Understanding this rate and maintaining it during backup is crucial for optimal tape drive performance.
Q4: How do I determine the transfer rate for my tape drive?
You can find the maximum raw (uncompressed) transfer rate in the tape drive’s documentation. For the minimum transfer rate, consult the manufacturer’s documentation or contact them if necessary.
Q5: Why is it essential to stay above the minimum transfer rate for tape drives? Falling below the minimum transfer rate can lead to performance issues as the drive writes data in short bursts. Staying above this rate ensures smooth and efficient operation.
Q6: What should I know about data transfer rates
You need to be aware of the data transfer rates of your servers and the compression ratios of your data. These factors affect the effective transfer rates and can impact backup performance.
