[OpenIndiana-discuss] SSD as a dedicated swap device

[Jim Klimov]

11 декабря 2015 г. 20:45:34 CET, Reginald Beardsley via openindiana-discuss <openindiana-discuss at openindiana.org> пишет:
>I have only occasional need to run problems larger than main memory (16
>GB at present), so  I can't justify replacing all the DRAM for an
>infrequent need.  The drop in SSD prices has me contemplating adding a
>128 GB SSD as a swap device.  The SSD latency and IOPS specs look as if
>they might be a useful compromise.
>
>Does anyone have any experience with this?  The sort of jobs I'm
>interested in are batch processes that take several hours, not
>interactive tasks.  
>
>At present rpool is a ZFS 3 way mirror.  It's become a bit unclear to
>me if it is still possible to control the swap device independently of
>other parts of the system contained in rpool.  Back in SunOS 4.x days I
>ran with a pair of swap partitions spread across two disks which got me
>twice the performance on large array operations.
>
>Reg
>
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I am hot sure I see a problem here. You can still make a raw partition and swap there, or a separate pool on the ssd and a zvol and swap there (there are some special options to optimize for the swap/dump zvols, see e.g. my OI/illumos wiki pages on "advanced" installs).

The swap area does not have to be part of rpool, and you can have more than one, and you can enable/disable them on the fly (free VirtMem space permitting). The only downside is that unlike linux you can't prioritize among your different active swap areas.

Jim
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