Tim Jones
Forum Replies Created
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[Raul Zeummes] “- why is bru adding ltfs functionality if the format itself is so bad ? the fact that they are doing that gives me the impression that ltfs is here to stay, and that it can’t be all that insecure if properly implemented.
We added support for LTFS for 3 reasons –
1 – When we added support to BRU PE for LTFS, we were simplifying the arcane command line mechanisms required to format, mount, check, and rollback LTFS tapes on OS X. Remember, when we launched less than 3 months after LTFS was announced, command line operations were the only option on OS X.
2 – We have customers receiving tapes in this format and wanted to allow them to use the same search mechanism for their LTFS tapes as for their BRU tapes.
3 – We wanted to provide a mechanism that would create properly formatted tapes every time in the instance that one of our customers had to use LTFS.– If the power cuts out during a backup (which I’m going to be doing all I can to avoid), I’m going to assume I’ve lost the data on the tape, and start the backup from scratch anyway.
Not required with BRU archives. Even if the power fails, the data that BRU has written to the tape is completely recoverable up to the point of failure. What if the failure also took out your disks? In that case, you couldn’t re-run the backup.
– is there a way to lose data during a read-only operation on ltfs due to a power loss ? (this would be much more worrisome)
Yes – because the filesystem is mounted, it can become corrupted just like a disk even if you’re only reading. There really isn’t a way to mount an LTFS volume as read only.
– when I came back to PRP after an overnight backup test (small, under 300gb), I had a mac system message that the software had crashed. But I also still had a window showing the details of the backup having been completed, and all the md5s having been completely verified. how often is it going to be crashing ?
I won’t be touching that one except to say that 300GB takes around 30minutes with BRU…
– from what I can tell so far, in PRP you can search your backup database for a file, and get the result, but if the tape containing that file is offline, you can’t get the file’s path. (using the print function) because you can’t put an offline file into the retrieval section
BRU can locate files on your media (BRU and/or LTFS) and provide the full path information of the selected files. If you then select those files for restore, you wil be told which tapes are required for the restore process. Also, the tapes don’t need to be online for a full search.
– how will PRP do on a backup test spanning multiple tapes ?
Doug? BRU will properly span tapes for a single backup or archival operation into the 16 Exabyte range.
– how will BRU do on the backup tests which I’ve started today ?
Hopefully I’ve answered that all above.
– I still have to look into PRP to see if there’s a way to compare a live file to a backup reference file in order to check if the live file has been corrupted for example
Because BRU’s proprietary format applies the 32bit CRC to the file data as it;s being read from the filesystem in 2K chunks, you will always be able to verify the tape’s contents WRT the file as it was read from the filesystem. If you wish, BRU will also allow you to performa a file by file comparison of the files in the archive against the original files on your system.
– apart from the power being cut during a backup, what are the other risks of using the PRP implementation of ltfs ?”
I don’t know that this is LTFS endemic or something the PRP has worked out, but you read the note about bad tapes when filling LTO-5 tapes in an LTO-6 drive (LINK), right? This is being fixed in the drive firmware for HP (done), Quantum (??), and Tandberg/Overland (??). I don’t know about IBM’s status. BRU does not suffer from this issue on any vendor’s tape drive.
What happens when you move to the next version of OS X or Windows and the FuSE layer hasn’t caught up? Since LTFS’s connection with your desktop and those apps that don’t natively write to tape is completely dependent on FuSE, and FuSE is a separate OSS project with no direct responsibility to the LTFS teams … I’m not trying to simply scare you here, we saw this with both Windows 7 SP 2, and OS X Mavericks. The FuSE layer was late arriving and if you made the OS switch early, you had no LTFS access.
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
D’oh – leaving my embarrassing previous post for posterity. That’s what I get for trying to read the COW on my iPhone…
The answer to your actual question ( 🙁 ) is still a no, but for a different reason. However, there is a way to do this with eSATA drives. You can connect an eSATA drive or box to the Atto ExpressSAS using this cable:
We use these with the ProBox from MediaSonic with success.
https://www.amazon.com/Mediasonic-HF2-SU3S2-ProBox-Drive-Enclosure/dp/B003X26VV4/
Again, sorry for the mis-direct in that last post…
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
[NOTE] – I answered the wrong question rather than what Eric actually asked 🙁 …
Hi Eric,It’s not possible at this time. A Japanese company was showing off a USB-3 LTO drive solution at NAB, but it can only be purchased as a complete unit and won’t be widely available for some time yet. They have achieved this by creating a USB-3 to single channel SAS converter.
Unitex Japan Portable LTO Solutions
The good news is that once it is available BRU supports it on OS X, Windows, Linux, and FreeBSD. There are limits to the performance on Windows because of the MS USB I/O stack limiting block sizes to 64K maximum, but it will work if more slowly than the native SAS versions.
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
The auto-backup feature executes every 15 minutes, but only if something has been modified…
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
What happens if you select the library in Finder and select “Show Package Contents”? Is anything there?
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
Hi John,
Great news. We were quite surprised that Apple “downgraded” the ATTO driver in Mavericks. We’ve discovered that both the ATTO driver in the OS and the older firmware contributed to less than stellar performance under Mavericks.
Tim
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
Hi John,
Start by opening a support ticket at support.bru.com. The guys will be glad to assist.
As an aside, what version of tapectl is on the 10.9.2 system? You can check this with:
tapectl -V
If it’s not 11.3 or 11.5, please reinstall the BRU PE package.
If it is, what do you get if you put the tape into the drive and execute these commands:
tapectl rewind
tapectl header | bru -gf –Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
What SAS HBA are you using? You can only use ATTO ExpressSAS HBAs for LTFS operations on OS X.
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
Chris – please don’t muddy the waters unnecessarily here. The drives that we are testing are not SMR drives, but “normal” (in light of what you’re talking about) disk drives.
The Seagate Model that we are looking at is the ST6000NM0024. It’s a 7200 RPM drive with 128MB cache and is rated capable of sustaining (versus bursting) 216MB/sec (we expect around 180MB in reality) with 1.4 million hours MTBF.
The HGST model (which is also the WD model since WD owns HGST) is the HUS726060ALA640. Also 7200RPM, 64MB/cache and is rated at 177MB/sec sustained (which is what we expect from the Seagate) with 2 million hours MTBF.
Note that NEITHER drive is a desktop drive, so the pricing will probably be very close to $100/TB (don’t expect bargains). Both drives offer around 8MS average seek time.
Neither of these drives is an SMR drive, so none of Chris’ comments or concerns about that technology will apply.
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters! -
Hi Joao –
No format required for BRU tapes. BRU uses the raw tape layer. Just pop the tape into the drive and tell BRU PE to write (overwrite a new tape since you can’t append to it 🙂 ).
Tim
Tim
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Tim Jones
CTO – TOLIS Group, Inc.
https://www.productionbackup.com
BRU … because it’s the RESTORE that matters!