Do VSI OpenVMS Drivers support Trim for SSD?

[John H. Reinhardt]

Cross posted from the VSI OpenVMS forum so if you have an answer, just post where you are most comfortable. :D

As a hobbyist, looking to put standard commercial SSD (Samsung EVO, WD Red, etc) in my Integrity rx2660. I already have some in my AlphaServer DS10's as data disks (unbootable). Just wondering is trim is available to help extend the life of the SSD.

The rx2660's disk controller is a P600 if that makes any difference. I also have a P400 available if that is a better option.

I read some posts from back in 2019 where Rod Regier (RIP) asked the same thing and in typical C.O.V. fashion it ended up a firestorm of opinions about, well anything other that what Rod wanted to know about trim.

Thanks

[Robert A. Brooks]

Post by John H. Reinhardt
Cross posted from the VSI OpenVMS forum so if you have an answer,
just post where you are most comfortable. :D
As a hobbyist, looking to put standard commercial SSD (Samsung EVO,
WD Red, etc) in my Integrity rx2660. I already have some in my
AlphaServer DS10's as data disks (unbootable). Just wondering is trim
is available to help extend the life of the SSD.

VSI VMS does not support the SCSI UNMAP command, which is needed for trimming.

HPE *did* implment the trimming aspect of thin provisioning, but we chose not
to accept those changes into our source pool, because we didn't like the code.

We think the HPE change was done in response to a request by a customer (for which
we suspect the customer paid). Apparently, the performance was so dreadful that
the customer chose not to use that feature.

[John H. Reinhardt]

Post by Robert A. Brooks

Post by John H. Reinhardt
Cross posted from the VSI OpenVMS forum so if you have an answer,
just post where you are most comfortable. :D
As a hobbyist, looking to put standard commercial SSD (Samsung EVO,
WD Red, etc) in my Integrity rx2660. I already have some in my
AlphaServer DS10's as data disks (unbootable). Just wondering is trim
is available to help extend the life of the SSD.

VSI VMS does not support the SCSI UNMAP command, which is needed for trimming.

Thanks Rob! I didn't think it had.

Post by Robert A. Brooks
HPE *did* implment the trimming aspect of thin provisioning, but we chose not
to accept those changes into our source pool, because we didn't like the code.
We think the HPE change was done in response to a request by a customer (for which
we suspect the customer paid).  Apparently, the performance was so dreadful that
the customer chose not to use that feature.

That's too bad Now that you mention this it does sound familiar, but my search didn't find it anywhere.

[Single Stage to Orbit]

Post by Robert A. Brooks

Post by John H. Reinhardt
Cross posted from the VSI OpenVMS forum so if you have an answer,
just post where you are most comfortable. :D
As a hobbyist, looking to put standard commercial SSD (Samsung EVO,
WD Red, etc) in my Integrity rx2660. I already have some in my
AlphaServer DS10's as data disks (unbootable). Just wondering is
trim is available to help extend the life of the SSD.

VSI VMS does not support the SCSI UNMAP command, which is needed for trimming.
HPE *did* implment the trimming aspect of thin provisioning, but we
chose not to accept those changes into our source pool, because we
didn't like
the code.
We think the HPE change was done in response to a request by a
customer (for which we suspect the customer paid).  Apparently, the
performance was so dreadful that the customer chose not to use that
feature.

All that's needed is a simple utility to run once a day, or a week or a
month to free up deleted data blocks on the devices. Linux has an
utility 'fstrim' that does this. I suggest implementing something like
this might be better rather than the half-assed solution that HP
dreamed up.

[Stephen Hoffman]

Post by John H. Reinhardt
Cross posted from the VSI OpenVMS forum so if you have an answer, just
post where you are most comfortable. :D
As a hobbyist, looking to put standard commercial SSD (Samsung EVO, WD
Red, etc) in my Integrity rx2660. I already have some in my AlphaServer
DS10's as data disks (unbootable). Just wondering is trim is available
to help extend the life of the SSD.
...

The HP "solution" was to initialize storage sectors to zero, and to
enable erase-on-delete to zero the deallocated storage, and to use an
SSD with support for that.

Some of the HPE 3PAR storage hardware supported this, as did some other
vendors. Check the specs, or check with the SSD vendor.

Wikipedia references this particular practice, too: "Regardless of
operating system, the drive can detect when the computer writes
all-zeros to a block, and de-allocate (trim) that block instead of
recording a block of zeros. If reading a de-allocated block always
returns zeros, this shortcut is transparent to the user, except for
faster writing (and reading) of all-zero blocks, in addition to the
usual benefit of faster writing into unused areas. Operating systems
don't write all-zeros to "wipe" files or free space, but some utilities
do." And contrary to that last sentence, the operating system here can
do exactly that.

This usage of writing sectors of zeros is different from writing
sectors of zeros for data remanence, but unfortunately these two
discussions tend to get tangled.

As mentioned elsewhere, no TRIM support in OpenVMS.