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I have a bunch of machines with HPE Smart Array P408i-a controllers and fully populated drive bays, and I was wondering if there is a way to extend the arrays without dissolving them and reinstalling everything.

There is a single RAID1+0 from 4x2 drives per machine, so considering the manual says "use replacement drives that have a capacity equal to or greater than the smallest drive in the array" it should be possible to mark one drive from each RAID1 pair as failed, replace it with a bigger one, have the controller rebuild everything, then do the same with the other part of the mirror. The question is, will the controller be smart enough to see the increased capacity after the second drive swap? These are all production machines so before I build a test setup for this rather lengthy procedure , maybe someone here has experience with this?

Update for posterity: it's a DL360 Gen10 running Linux; ssacli says:

HPE Smart Array P408i-a SR Gen10 in Slot 0 (Embedded)

   Internal Drive Cage at Port 1I, Box 1, OK
   Internal Drive Cage at Port 2I, Box 1, OK
   Port Name: 1I (Mixed)
   Port Name: 2I (Mixed)

   Array A (SAS, Unused Space: 0  MB)
      logicaldrive 1 (6.55 TB, RAID 1+0, OK)

      physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SAS HDD, 1.8 TB, OK)
      physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SAS HDD, 1.8 TB, OK)
      physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SAS HDD, 1.8 TB, OK)
      physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SAS HDD, 1.8 TB, OK)
      physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SAS HDD, 1.8 TB, OK)
      physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SAS HDD, 1.8 TB, OK)
      physicaldrive 2I:1:7 (port 2I:box 1:bay 7, SAS HDD, 1.8 TB, OK)
      physicaldrive 2I:1:8 (port 2I:box 1:bay 8, SAS HDD, 1.8 TB, OK)

   SEP (Vendor ID HPE, Model Smart Adapter) 379
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  • Can you provide details on OS, server model (Gen10), the disks currently in use, the disks you plan to use, and possibly the output from the ssacli program: ctrl all show config ?
    – ewwhite
    Nov 15, 2022 at 13:28

2 Answers 2

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Yes this works. Use similar drive types.

You can replace one drive at a time and wait for the rebuilds.
At the conclusion of ALL EIGHT DRIVES being rebuilt, you'll see additional space available to grow the Logical Drive.

But how did you get into this situation?

This may be an opportunity to refactor and redesign...

Often times people in this situation can move to RAID6 or RAID5 on the same group of drives to gain additional space. This is a good approach if the workload doesn't require RAID 1+0 performance.

Another option is to add a SAS expander and another 8-bay drive cage (assuming DL380/DL385 Gen10 hardware). That would allow expansion to 16 or 24 disks.

I asked about the size and type of drives in use because this sounds like standard SAS 2.5". These drives have not grown substantially in size of the years (300GB, 600GB, 900GB, 1.2TB, 2.4TB), so there may be marginal gains in going through a lengthy drive replacement/rebuild/replacement cycle.

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  • Thank you! So say 2x2x1.8TB + 2x2x2.4TB wouldn't work? We have 8x1.8 and would move to either the above or 8x2.4. One of the services on the machines has a fairly slow but steady database growth to an extra TB or two should give us enough time now. There's a whole bunch of backends on there though so I suppose RAID5/6 could get tight WRT write performance.
    – mbethke
    Nov 16, 2022 at 10:04
  • 2x2x1.8TB + 2x2x2.4TB would not give you more space. 8 x 2.4 WILL work, but that's not a large increase. You would go from 7.2TB to 9.6TB usable if you swapped to 8 x 2.4. But if you take my suggestion to convert to RAID5, you'd get 12.6TB usable with no appreciable difference in performance.
    – ewwhite
    Nov 16, 2022 at 10:46
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Not done this for a long time but it should be possible.

https://support.hpe.com/hpesc/public/docDisplay?docId=c03909334

Just make sure you use the same type of disks so no mixing of SAS or SATA.

You didn't mention your OS running on the machines, which will need a supported process of expanding the file system to take advantage of the extra array space.

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  • Thanks! Yes, we have all SAS disks, and there's Linux with LVM and ext4 on top of it, so online resizing is fine.
    – mbethke
    Nov 16, 2022 at 10:03

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