The original SNAP NAS devices were developed by SNAP Appliance. The operating system that was used was a flavor of BSD in concert with the file system UFS. Although the file system looks very similar to the original UFS there were some subtle changes made. View It Now takes those changes into consideration when searching and building a virtual drive. Although the majority of View It Now makes the mechanics of the file system transparent to the technician there are some things that still need to be addressed in a ‘native mode’ manner. The following are a list of options/functions that are specific to the SNAP OS 4.x version of View It Now.
Verify Cylinder Groups
The SNAP OS file system is very similar to many Linux/Unix type file systems. The file system is spread across the entire drive with many little sub-groups that maintain a microcosm of the entire file system. Some file systems call these groups ‘Allocation Groups‘, others call them ‘Block Groups‘, and this file system uses the label ‘Cylinder Groups‘.
The reason that groups are used is to allow the file system to manage the hard drive in such a way as to keep wide seeks to a minimum. For instance, if you have a database that is spread across an entire drive due to fragmentation you get the heads moving up and down across the drive which causes unnecessary heat, wear, and time to read or write data. If the data is kept in a smaller area then the drive will have shorter seeks, hopefully contiguous reads, and a more stable file system.
All of this being said each cylinder group has its own set of inodes, a data set area, a block bitmap and other system data. The report takes a look at some of the system information to try and determine if the cylinder groups are in alignment. To execute the report use the following steps.
- 1. Make sure that a volume is mounted. Refer to View It Now documentation to see how to mount a volume.
- 2. Move the mouse to the ‘Volume Tools‘ item on the menu bar and click. You will be presented with a drop-down menu.
- 3. From the drop-down menu select the item labeled ‘Verify Cylinder Groups‘ and click on it. The testing will begin.
- 4. To monitor the progress of the test look in the ‘Search Information‘ group box. The ‘Block‘ label will indicate which cylinder group is being tested, and how many total cylinder groups are in this particular volume.
- 5. Once the test is finished a dialog box will appear indication how many cylinder groups did not pass the test.
The comments below are for users to ask questions and request product updates.
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I experienced a failed disk in a mirrored pair in a Snap Server. I cloned the failed one with a sector copier. With this clone connected to my regular Windows box via USB, the Snap OS File Viewer shows entries for all the files I can no longer access.
This is maybe a sophomoric question, but “now what”? I can’t copy, transfer or rescue these files in any way, all I can do is see that they seem to still be stored on the drive.
The working drive remained in the Snap, and would not display anything so I asked it to do a soft recover. It did, and the Snap functions but displays an empty file structure.
I have done some medium-level recovery before with FAT, NTFS, and Mac, but this is alien to me. I can’t look at it with a hex editor because the system does not recognize the disk.
Any comments or hints would be welcome!
Jeff
Followup: I was not aware of WinHex, I have been using HexEd. With WinHex, I was able to explore the content of the drive even though Windows does not recognize it. I am very happy to be steered toward WinHex, it really is something special.
I’ll see what I can do from here. Thanks for the tip!
Hello,
I have a Lacie external harddrive which does not show up on the computer (no drive letter) , I think partition (maybe have been deleted or corrupted) might be missing. Problem showed up after formatting and then trying to clone to it. I used ”Partition Repair” and can now see the drive and when I click on it the boot and all other settings are zeroes. I cannot edit any of the settings either. Is there anything I can do to reset the sttings in Patition Repair or How can I rewrite a boot partition to it? Thank you.
Phil,
Is the drive slow in coming up? Was the LaCie slow to format? If you formatted the drive then you should see data in the partition table of the software.
You either have:
1. Bad sector 0
2. Cloned the wrong direction
3. Intermittent USB interface problems
What I would do would be to format it again and see if it shows a drive letter. If it does not then look at it with the partition repair tool. If the display is still zeroes then the interface or the drive is bad.
Lastly, I am assuming that you are not concerned about the data since you formatted the LaCie
Dick
I ran VIN-SNAP on a 160 gig drive and received a read error at block 216 of 39266:
FUNC:() MSG:() LBA:(0) NUM(0)
When I click OK on the error message, the program closes. Is there anything I can do with this? Thanks.
Dick, do you know of ANY other OS that will mount the SnapOS HHD ? Do you know of any other OS that will be able to see the mounted SnapOS HHD ?
Thank you for your expert knowledge.
Best regards,