Issue with hot-plugging drives
Posted: Thu Nov 11, 2010 7:55 am
Hi again,
I found an issue with hot-plugging drives. FC for Disk 0.3.0.0. For example:
SATA0: SSD1
SATA1: no drive
SATA3: SSD2 (boot disk)
SATA4: Spinning disk
I cache the boot disk (C:) on SATA3.
Now when I hot-plug a drive on SATA1, I get the following.
SATA0: SSD1
SATA1: Spinning disk
SATA3: SSD2 (boot disk)
SATA4: Spinning disk
As you can see, the boot disk C: has moved down. It is no longer the second disk; it's now the third disk in line.
This causes FC to fail and stop caching the C: drive althogether. You will know that hot-plugging is very common in production environments.
Perhaps you could identify the disk to be cached irrespective of its relative position on the SATA hub.
For example, identify it by a combination of its disk label, its serial number, drive type, or whatever.
You don't have to do this in realtime on a running system; just do it during driver initialization at boot time.
Not a big problem, because FC is already smart enough to turn off caching when the disk order changes. I found no corruption while hot-swapping disks.
Yet if you want to sell FC to companies and other professional environments, you need to handle hot swapping properly.
I understand the problems so maybe you could fix it in a future major release. You don't have to fix it rightaway.
I found an issue with hot-plugging drives. FC for Disk 0.3.0.0. For example:
SATA0: SSD1
SATA1: no drive
SATA3: SSD2 (boot disk)
SATA4: Spinning disk
I cache the boot disk (C:) on SATA3.
Now when I hot-plug a drive on SATA1, I get the following.
SATA0: SSD1
SATA1: Spinning disk
SATA3: SSD2 (boot disk)
SATA4: Spinning disk
As you can see, the boot disk C: has moved down. It is no longer the second disk; it's now the third disk in line.
This causes FC to fail and stop caching the C: drive althogether. You will know that hot-plugging is very common in production environments.
Perhaps you could identify the disk to be cached irrespective of its relative position on the SATA hub.
For example, identify it by a combination of its disk label, its serial number, drive type, or whatever.
You don't have to do this in realtime on a running system; just do it during driver initialization at boot time.
Not a big problem, because FC is already smart enough to turn off caching when the disk order changes. I found no corruption while hot-swapping disks.
Yet if you want to sell FC to companies and other professional environments, you need to handle hot swapping properly.
I understand the problems so maybe you could fix it in a future major release. You don't have to fix it rightaway.