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Re: What's my best expansion strategy?

Sunday_Afterno1
Aspirant

What's my best expansion strategy?

Hi everyone,

Here is my current Pro Business Edition disk configuration by slot. My volume is XRAID2 with single redundancy and was created well before 4k blocks were a consideration. From my initrd.log file it looks like the volume was created on 4.2.5.


  1. 2TB Hitachi

  2. 2TB Hitachi

  3. 2TB Hitachi

  4. 2TB Hitachi

  5. 1.5TB Seagate

  6. 1.5TB Seagate


  7. I need to expand my volume to include 3TB drives and would welcome advice on the most efficient way to do this, if possible making use of the new 4k block size. An obvious upgrade appears to be to replace the 1.5 TB drives with 3TB ones and then progressively replace the 2TB with 3TB.

    Can someone give some pointers on how the ReadyNAS copes with new drives that are 4k capable?

    • Does the NAS take advantage of the advanced format for these drives individually to use the full capacity available?

    • From partition.log the start sector for 4 of my drives is 4. 2 recent replacement drives have a start sector of 8.

    • I read a post by mdgm that I can force the start sector to be reset by hot-removing and re-syncing each start sector 4 drive in turn. Is this advisable?

    • What are my considerations regarding the 16TB volume limit that I see mentioned?


    Thanks very much!
Message 1 of 7
TeknoJnky
Hero

Re: What's my best expansion strategy?

Sunday Afternoon wrote:

Here is my current Pro Business Edition disk configuration by slot. My volume is XRAID2 with single redundancy and was created well before 4k blocks were a consideration. From my initrd.log file it looks like the volume was created on 4.2.5.


  1. 2TB Hitachi

  2. 2TB Hitachi

  3. 2TB Hitachi

  4. 2TB Hitachi

  5. 1.5TB Seagate

  6. 1.5TB Seagate


  7. I need to expand my volume to include 3TB drives and would welcome advice on the most efficient way to do this, if possible making use of the new 4k block size. An obvious upgrade appears to be to replace the 1.5 TB drives with 3TB ones and then progressively replace the 2TB with 3TB.


essentially yes. However, if you don't replace them all within the same time period, then you will need to resync each of the drives you don't replace in order for the new drives to expand.

When a drive is resync'ed (hot removed, then hot re-added), the nas will update the partition to be compatible with 4k sectors.

All drives my be the same alignment (either all 4k aligned, or all old-default align) to expand.


Can someone give some pointers on how the ReadyNAS copes with new drives that are 4k capable?

  • Does the NAS take advantage of the advanced format for these drives individually to use the full capacity available?

  • From partition.log the start sector for 4 of my drives is 4. 2 recent replacement drives have a start sector of 8.

  • I read a post by mdgm that I can force the start sector to be reset by hot-removing and re-syncing each start sector 4 drive in turn. Is this advisable?

  • What are my considerations regarding the 16TB volume limit that I see mentioned?



1) the 4k sector alignment is really a performance consideration, not necessarily anything to do with space. If the partitions are not aligned on 4k, then writes speed will be reduced.

2) then these particular drives have been 4k realigned already, see above regarding resyncing drives

3) yes, see above

4) 6x 3tb drives will not exceed the 16tb drive limit, so you have nothing to worry about there. Hopefully by the time the 3.5 or 4tb drives come around, the 16tb limit will be fixed. But if not, then your only option would be to backup, factory default with all drives in place, then restore data.

4b) you may or may not come up against the 8tb online expansion limit, but that just means that expansion will happen offline when you reboot (you won't be able to access your data until expansion completes).
Message 2 of 7
TeknoJnky
Hero

Re: What's my best expansion strategy?

oh also, since this array was created before ext4 was the default, there may be expansion issues from having a non-native ext4 filesystem.

The jedi's or someone more knowledgable will have to answer that.

If there are issues, then your option will be to backup, factory default, restore.
Message 3 of 7
Sunday_Afterno1
Aspirant

Re: What's my best expansion strategy?

Thanks for the advice.

TeknoJnky wrote:
oh also, since this array was created before ext4 was the default, there may be expansion issues from having a non-native ext4 filesystem.


Is there a way to tell in the logs? Last month I replaced a 1.5 TB Seagate with the 2TB Hitachi drive in slot 4. (This must be one of the drives with the first sector starting at 8.) Expansion to use the additional 500GB went fine.

A long time ago now I did have a problem expanding. I think that this was when I added the 1.5TB drives alongside the original 1TB drives. I needed support's help and they ssh'd in and fixed whatever was preventing expansion from occurring. You have me thinking that this might have been caused by the non-native ext4 filesystem you mention above.
Message 4 of 7
Sunday_Afterno1
Aspirant

Re: What's my best expansion strategy?

A quick update - I'm now waiting for the new 3TB drives to arrive. I was surprised to learn that 3TB desktop Hitachi drives include Rotational Vibration Protection. They should be here tomorrow.

In preparation I tested the disks using the Boot Menu option. Once that completed successfully I hot-pulled and replaced each drive one-at-a-time to force the sector realignment as the array is rebuilt. I'll update once the 3TB drives are installed.
Message 5 of 7
Sunday_Afterno1
Aspirant

Re: What's my best expansion strategy?

The first Seagate 1.5TB drive has been replaced by a 3TB Hitachi one.

The array has been rebuilt successfully and expansion to include the extra 500 GB to match with the 2TB drives proceeded automatically. The real test comes tonight with the installation of the second 3TB drive. Will the extra 1 TB expansion work?
Message 6 of 7
Sunday_Afterno1
Aspirant

Re: What's my best expansion strategy?

As I said yesterday, the real test is the next drive replacement. Unfortunately, the first of the new Hitachi 3TB drives threw ATA errors during the rebuild and I now have a volume in life suport mode. New thread started with support case (16393961) in title: viewtopic.php?f=66&t=55910
Message 7 of 7
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