Re: 8203-E4A RAID5 vs. ASP protection

In the newer systems we can add drives to RAID, format them, and add them to the ASP with the system running. Performance was not seriously impacted so we used to do it all the time.

With a SAN you’ll never notice the format and add process except in very extreme cases where the SAN is already under I/O stress.

If you just add a drive unit (even with you’re level of software) the system will recognize it automatically and then you do what needs to be done. No rescan needed, the controller card is smart enough to handle it.


Jim Oberholtzer
Agile Technology Architects

On Mar 2, 2024, at 12:41 PM, Patrik Schindler <poc@xxxxxxxxxx> wrote:

Hello Jim,

Am 02.03.2024 um 16:49 schrieb Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>:

If the customer wanted to add three drives to fill the chassis up, the system would try to create a new RAID set as opposed to adding the drives to the current set. It would fail since it needed four units at the time. So we would do it twice, once with two, then the single. With only two units it would simply add them to the current RAID set.

I see, thanks!

Technically the best plan would be to stop RAID and restart it to get the RAID striping across all the drives but as you discovered that was a really long process most customers would not tolerate.

Well, building runs in the background, once the initial processing has been done in DST. But it's a serious brake to system performance. Not sure if adding newly plugged disks to RAID can be entirely done in SST. I believe just adding to an ASP works. I don't know how to force a rescan for disk devices, though.

:wq! PoC



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