User manual

SANtools® S.M.A.R.T. Disk Monitor (SMARTMon-UX)28

You may use either smartmon-ux -h or smartmon-ux -? to get help and usage information. As many UNIX/

LINUX shells substitute the '?' character for a single-byte wild-card, you should just enter smartmon-ux -h for help,

which will work for all operating systems and shells.

1.6 Change Block Size

Invoke the -capacitybs command to change the block size of your random access device.

Usage

smartmon-ux -capacitybs NewBytesPerBlock DeviceList

Example

smartmon-ux -capacitybs 520 /dev/sg3 (sets the block size to 520 bytes/block)

With few exceptions, disk drives are set to 512 bytes per block, and operating systems expect disks to be formatted to

512 bytes per block. In fact, some operating systems and/or disk controllers won't even "see" disks that aren't

formatted to 512 bytes/block. This command exists because certain RAID controllers require disks to be formatted to

520 or 528 bytes/block. If the disk isn't formatted to the appropriate block size then it just won't work with the required

hardware. Once this command has been accepted by the disk, and you invoke the -format function to reformat

the disk, then you should be able to use it.

Warnings & Caveats

Once the block size is successfully changed, you need to power cycle the disk drive and use the -format command

to complete the operation. You can not use the disk drive until you reformat it.

RAID subsystem manufacturers have little motivation for allowing end-users to add their own disk drives. This isn't

just for financial reasons, but for data integrity and reliability concerns. Furthermore, RAID subsystem manufacturers

invest a significant amount of R&D in having customized drive firmware. As such, even if you take an off-the-shelf

disk drive, and change the blocks size and all of the mode page settings to get it to match your RAID vendor's disk

drive, then the RAID engine may still reject the disk.

SANtools is bound by numerous non-disclosure arrangements and we will not provide any advice relating to how one

might reprogram or reformat a disk so you can get it to work in a specific RAID subsystem.

Let's say that you have the opposite problem. You purchased used disk drives and it turns out that you can't format

them because they aren't formatted to 512 bytes/block. You still have risk that the firmware on those disk drives will

reject commands to change the block size. It is not uncommon to have disk drives with specialized firmware that

prevents you from changing the block size. If the disk rejects the -capacitybs command, then the only way to

change the block size is to flash new firmware on the disk drive. (Not just new firmware, but the correct firmware file)

As your disk drive firmware isn't our intellectual property, we are morally and legally prevented from sending anybody

firmware.

The bottom line is that some disk/firmware combinations let you change the block size, and some don't. If your disk

rejects the -capacitybs command, then you must call your drive supplier/vendor, and ask them about getting some

firmware that will let you change the block size.

1.7 Change Disk Capacity

The -capacity command is used to resize the number of blocks that a disk reports. You would use it to short-

stroke a disk (resize the disk to make it smaller). Once you resize the disk with the command, then you can use the

resized disk immediately, and it does not need to be reformatted. This function can be quite useful, either to hide a

partition on a disk, or to unlock space that was hidden by your hardware supplier.

You may reverse the effects of changing capacity by sending it a new size of 0. This will allocate all available disk

space, and cause the disk to report the full factory-configured capacity.