- March 22, 2019 at 1:07 am
Hi folks, last post here was maybe some ten years back.
I recently acquired an lto 6 drive from ibm. It connects over sas to a windows 7 machine.
I am using ibm ltfs 2.2 tool to format the media to ltfs. It works and I copied more than 1tb of data just fine, only to realize that it is using compression. DPX sequences for instance come out some 20% smaller in size than they are. Sadly my clients want no compression.
I read compression is enabled by default in the ibm tool, and can`t seem to find a way to disable it when formatting. BTW I am using the command promt to format as the gui or right click tools don´t seem to work for some reason. Does anybody know a way I can format with compression disabled?
Thanks a lot for your time
- March 22, 2019 at 12:06 pm
I don’t see what the big deal with compression is because its transparently done by the drive itself and every drive understands it so there’s no chance that a compressed tape won’t be readable anytime in the future unlike some proprietary compression algorithms some backup programs use. You don’t lose anything by having it on because the drive determines if the data is compressible and if it isn’t it just simply writes out the raw data, either way it writes out a flag to say whether the next record is compressed or not and reading the tape simply involves reading the flag and processing the data by uncompressing it accordingly if needs be. I guess the only negative is if someone gets accustomed to say writing 3TB of compressible data to a 2.5TB LTO6 tape and the next time they try to write out 3TB of uncompressible data to the same tape and then find out it doesn’t fit but other than that there aren’t any other negatives that I can see so perhaps you can advise them their concerns are unfounded, anyway to answer your question try doing what this article here says https://www.ibm.com/support/knowledgecenter/en/linuxonibm/com.ibm.linux.z.lgdd/lgdd_t_tape_wrk_comp.html however, it may be turned on in LTFS so there may be a setting you may need to clear when you format the tape like this https://i.imgur.com/Hb4fYNs.png
- March 22, 2019 at 5:34 pm
Thanks Jerzy, I agree with you about compression, but don`t think I can talk them into accepting it.
The command line method you point me to is for linux. I installed ubuntu 17 on the machine just to find ibm ltfs does not support it. May have to look for something else.
The png you show me is for the hp software, wich does not seem to work with an ibm drive (i tried).
It have now installed the drive on a osx 10.8.5 machine and it is recognized and can operate but I am now in search for ibm ltfs 1.3 for mac, as it seems the later versions dropped support for my os. Problem is ibm only lists version 2.2 and above, wich do not work.
Thanks again, will see what I can find, don´t have much time…
- September 9, 2019 at 7:17 am
dear Pepo Razzari,
I know I have been jumping on to an older post. Did you figured this out?
I read somewhere in the ibm website, if you’re using an IBM drive in MAC OS X while you are formatting a new tape using terminal just add -c with value 1 or 0 to should enable or disable the compression on your drive.
I don’t have any exact idea which number is for disable. I am using an HP drive now so can’t confirm it. Just try it if you still facing the issue or just ignore.
HARI KRISHNA PUNE
FCP EDITOR & ARCHIVE MANAGER
- January 4, 2021 at 6:13 pm
The big win here is to get the user to understand that the compression used for DATA is not the same as compression used for transcoding. Transcoding is a lossy (on purpose) type of operation. We know that when we transcode a file to another format, bitrate, etc., that we will lose data. The compression used for DATA is lossless – meaning that you get 100% of what you put in back after compression and decompression. And, LTO-‘s mechanism is adaptive in that if the algorithm cannot compress the data (which is true with most M&E content), it passes the data through to the tape uncompressed, anyway.
Imagine if your bank backed up your records to LTO and when they had to restore your data, you now only had $3.00 in your account instead of $3,000. That definitely would not pass any form of use, security, or standards examination.
You will never lose fidelity or content allowing the tape drive to manage the compression automatically. We (the tape industry) created it to operate that way on purpose.
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