4 messages, 3 authors, 2011-02-07 · open the first message on its own page
From: Henrik Olsson <hidden>
Date: 2011-02-07 11:41:13
Hi, One of the drives in my raid1 recently crashed and it looks like all the replacement disks (2TB) i can find use 4K sectors, but the old ones were 512 bytes. Are there any issues with having a raid1 array with different sector sizes for the drives? Regards, Henrik
From: David Brown <hidden>
Date: 2011-02-07 13:56:04
On 07/02/2011 12:41, Henrik Olsson wrote:
Hi, One of the drives in my raid1 recently crashed and it looks like all the replacement disks (2TB) i can find use 4K sectors, but the old ones were 512 bytes. Are there any issues with having a raid1 array with different sector sizes for the drives? Regards, Henrik
I can't answer for sure, but I would think there would be no problem as long as you make sure your partitions are 4 KB aligned. AFAIUI, Linux always writes in 4K blocks to the disks anyway, so alignment is the only issue - and that's a performance issue, not a correctness one.
From: Henrik Olsson <hidden>
Date: 2011-02-07 14:08:17
On Mon, Feb 7, 2011 at 14:56, David Brown [off-list ref] wrote:
On 07/02/2011 12:41, Henrik Olsson wrote:quoted
Hi, One of the drives in my raid1 recently crashed and it looks like all the replacement disks (2TB) i can find use 4K sectors, but the old ones were 512 bytes. Are there any issues with having a raid1 array with different sector sizes for the drives? Regards, HenrikI can't answer for sure, but I would think there would be no problem as long as you make sure your partitions are 4 KB aligned. AFAIUI, Linux always writes in 4K blocks to the disks anyway, so alignment is the only issue - and that's a performance issue, not a correctness one.
Yes, that's the impression i've gotten after reading about it too. As long as i create a 4KB aligned partition on the new drive that is at least as large as the old one and replace the old one with it in the array, it should just work? I run dmcrypt and then lvm on top of the raid array though, trying to figure out what needs to be done with alignment with those... Worst case i should be able to create a new properly aligned array/dmcrypt/lvm on the new drive, copy the old data over and add the old working drive to the new array since if it's 4K aligned it should also be 512B aligned? /Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Roberto Spadim <hidden>
Date: 2011-02-07 15:07:39
speed problem =) (i tested eeheheh) i was talking about it in this list i don´t know yet what the internal raid1 sector size (i think it´s the chuck size defined on mdadm --create, but i´m not sure) if you use 4k ssd you can see read/write when making <4kb read on ssd, if it's a hd no problem, ssd will degrade max ssd speed with wrong sector size (read/write not aligned) i'm waiting the chunck size answer if you want wait the list to answer... 2011/2/7 Henrik Olsson [off-list ref]:
Hi, One of the drives in my raid1 recently crashed and it looks like all the replacement disks (2TB) i can find use 4K sectors, but the old ones were 512 bytes. Are there any issues with having a raid1 array with different sector sizes for the drives? Regards, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html