dzog
Cadet
- Joined
- Apr 12, 2017
- Messages
- 7
Hey folks!
Currently building my first FreeNAS server.
When I built arrays on other platforms, I would always partition the disks to be slightly smaller than the rated size in order to allow for fluctuations between "same-sized" drives in the future when replacements are needed and the exact original drives may be unavailable or prohibitively expensive for whatever reason.
When looking into whether or not FreeNAS does something like this automatically, or otherwise easily allows for it, I discovered that FreeNAS creates 2GiB swap partitions on all my disks when adding them to a volume:
It looks like these are active swap used by the OS:
This led me to some thoughts/observations:
- The 2GiB swap partition does turn my 8,001,563,222,016 byte (~8001.56 GB) disks down to a more comfortable 7,999,415,648,256 bytes (~7999.42 GB) actually used as vdev members
- Other than the swap space, FreeNAS does appear to use the entire disk (e.g. no specific provision for "very slightly smaller replacement disks")
- If I wanted to replace a drive with a slightly smaller variant, it seems I could just cut down on swap spaced used to make it work. I'm curious: is this something that FreeNAS would handle by itself when I went to replace a disk in the GUI, or would I need to manually make things happen in the shell?
- What's up with the swap space? Will FreeNAS really swap RAM into bare partitions on spinny disks instead of to, say, a zfs volume? Doesn't that seem kind of unsafe, or at least more dangerous than being in ECC RAM?
- How do others proactively solve for the "8TB disks can all be different sizes (pretty close to and hopefully at/exceeding 8.0e12 bytes)?" problem when dealing with replacements down the road?
Currently building my first FreeNAS server.
When I built arrays on other platforms, I would always partition the disks to be slightly smaller than the rated size in order to allow for fluctuations between "same-sized" drives in the future when replacements are needed and the exact original drives may be unavailable or prohibitively expensive for whatever reason.
When looking into whether or not FreeNAS does something like this automatically, or otherwise easily allows for it, I discovered that FreeNAS creates 2GiB swap partitions on all my disks when adding them to a volume:
Code:
root@freenas:/dev # gpart show /dev/da0 => 40 15628053088 da0 GPT (7.3T) 40 88 - free - (44K) 128 4194304 1 freebsd-swap (2.0G) 4194432 15623858688 2 freebsd-zfs (7.3T) 15628053120 8 - free - (4.0K)
It looks like these are active swap used by the OS:
Code:
root@freenas:/dev # swapinfo Device 1K-blocks Used Avail Capacity /dev/ada0p1.eli 2097152 0 2097152 0% /dev/ada1p1.eli 2097152 0 2097152 0% /dev/da0p1.eli 2097152 0 2097152 0% /dev/da1p1.eli 2097152 0 2097152 0% /dev/da2p1.eli 2097152 0 2097152 0% /dev/da7p1.eli 2097152 0 2097152 0% /dev/ada2p1.eli 2097152 0 2097152 0% /dev/ada3p1.eli 2097152 0 2097152 0% /dev/da3p1.eli 2097152 0 2097152 0% /dev/da4p1.eli 2097152 0 2097152 0% /dev/da5p1.eli 2097152 0 2097152 0% /dev/da6p1.eli 2097152 0 2097152 0% Total 25165824 0 25165824 0%
This led me to some thoughts/observations:
- The 2GiB swap partition does turn my 8,001,563,222,016 byte (~8001.56 GB) disks down to a more comfortable 7,999,415,648,256 bytes (~7999.42 GB) actually used as vdev members
- Other than the swap space, FreeNAS does appear to use the entire disk (e.g. no specific provision for "very slightly smaller replacement disks")
- If I wanted to replace a drive with a slightly smaller variant, it seems I could just cut down on swap spaced used to make it work. I'm curious: is this something that FreeNAS would handle by itself when I went to replace a disk in the GUI, or would I need to manually make things happen in the shell?
- What's up with the swap space? Will FreeNAS really swap RAM into bare partitions on spinny disks instead of to, say, a zfs volume? Doesn't that seem kind of unsafe, or at least more dangerous than being in ECC RAM?
- How do others proactively solve for the "8TB disks can all be different sizes (pretty close to and hopefully at/exceeding 8.0e12 bytes)?" problem when dealing with replacements down the road?
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