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I have a RAID 5 with 5 3TB drives (8 in few weeks), on a Debian. There is only one ext4 partition on it, using all the space available.

Actually, due to origins of the RAID (4 drives), the ext4 fs stripe-width is set to 384. But with 5 drives, it's not good.

So, is it possible to update stripe-width with tune2fs ( tune2fs -E stripe-width=512 ) on the unmounted ext4 partition, without data loss ?

Thanks

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Stripe width of the filesystem is just a parameter used to optimise the pattern of writes. You can change it on an existing partition and it will be used when writing new data.

However a RAID5 with 3TB drives isn't very safe, you should think about using RAID6 at least.

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  • Thanks, it's updated now, with success :) RAID6 is planned with the big drives update. It's not perfect, but it's already something (maybe a true secured mirroring in months). – Moff Tigriss Jan 28 '15 at 15:57
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Yes you can change that setting. Though unfortunately your filesystem layout would not be affected. It's only going to change how things are written in the future. See the below man page excerpt. Sounds like you're better off recreating the filesystem if it continues to be a problem and it's feasible. Like it says below, it's mostly mkfs that benefits from this setting.

man tune2fs

stride=stride-size Configure the filesystem for a RAID array with stride-size filesystem blocks. This is the number of blocks read or writ‐ ten to disk before moving to next disk. This mostly affects placement of filesystem metadata like bitmaps at mke2fs(2) time to avoid placing them on a single disk, which can hurt the performance. It may also be used by block allocator.

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  • The OP asked about stripe-width, not stride-size. – Jakub Klinkovský Oct 14 '20 at 16:32

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