I wondered if anyone could explain something I am seeing with a SLOG device I added recently.
First off, I have read everything on adding a log device and know why to add it and why I added it (Mac OS smb copies using 'sync'.) I did find some behavior today which conflicts with what I have read though and wanted to ask if anyone knows why.
I have a couple of different shares on the pool that is backed by a SLOG device (Optane 900p.) I get expected performance out of this when using the share I have designated as 'sync = always', and it greatly improves the sync performance. Obviously, async is still faster, so I have another share on this same pool that has 'sync=standard'. I expected the SLOG device to not be used at all when writing to this share, but it s used a bit. I see small 30Kb/s-50Kb/s writes constant to it when copying to an async share with periodic spikes to 250Kb/s. I have no problem with this, but I wondered if anyone knew why it does this from a technical perspective. Where would these writes have gone without a log device, and what are they?
thanks for any perspective,
First off, I have read everything on adding a log device and know why to add it and why I added it (Mac OS smb copies using 'sync'.) I did find some behavior today which conflicts with what I have read though and wanted to ask if anyone knows why.
I have a couple of different shares on the pool that is backed by a SLOG device (Optane 900p.) I get expected performance out of this when using the share I have designated as 'sync = always', and it greatly improves the sync performance. Obviously, async is still faster, so I have another share on this same pool that has 'sync=standard'. I expected the SLOG device to not be used at all when writing to this share, but it s used a bit. I see small 30Kb/s-50Kb/s writes constant to it when copying to an async share with periodic spikes to 250Kb/s. I have no problem with this, but I wondered if anyone knew why it does this from a technical perspective. Where would these writes have gone without a log device, and what are they?
thanks for any perspective,