Byte-for-Byte verify fails using IFW but not IFL

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Re: Byte-for-Byte verify fails using IFW but not IFL

Postby TeraByte Support » Tue Jul 04, 2017 11:15 pm

most of these new Samsung's don't have DRAT. Without DRAT, things that
check integrity can't always be used. Causes a bunch of validation failure
and required fixes when used with RAID as well. They say the Pro is
supposed to have it, but you can't find much information on it, they don't
list that.


"timg11" wrote in message news:13971@public.image...

I'm having the same issues.

I recently replaced the SSD in my HTPC (Win 7 /32). It had been backing up
with IFW and PhyLock for several years without issues.
Now I installed a Samsung 850 EVO, and I'm getting consistent byte for byte
validation failures every time in IFW 3.08.

Nothing else changed (other than the size which went from 64G to 120G).

I tried multiple times, writing the image to a local drive, to a network
drive, and I tried the "disable trim"option in settings. In all cases there
is a byte-for-byte verify error.

Tell me more about Deterministic Trim? Is there a firmware update or other
settings that can fix the issue?
I have searched for firmware updates for the SSD, but I do not find any for
the 850 evo.

Thanks!



[7/4/2017 9:04:30 AM] Byte-for-Byte failure at LBA 10926911 offset 0 (32768)
[7/4/2017 9:04:30 AM] Byte-for-Byte comparison failed.
Do not abort if you want to ignore these errors.



[7/4/2017 4:28:12 PM] Byte-for-Byte failure at LBA 11854079 offset 0 (40960)
[7/4/2017 4:28:12 PM] Byte-for-Byte failure at LBA 11854087 offset 0 (45056)
[7/4/2017 4:28:12 PM] Byte-for-Byte comparison failed.
Do not abort if you want to ignore these errors.

TeraByte Support
 
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Re: Byte-for-Byte verify fails using IFW but not IFL

Postby timg11 » Wed Jul 05, 2017 9:21 am

Well DRAT, it's a shame there is no workaround. I think my last 850 EVO is still in the returnable period with Amazon, so back it goes for a Crucial or Intel.

I propose a sticky announcement post at the top of this forum to the effect, "Do not buy Samsung 800 series SATA SSDs if you plan to image with IFW or IFL and plan to use byte for byte verification"

It looks like the Samsung NVMe SSD 950 using M.2 are OK. I have that in my main development machine, and do not see any errors.
timg11
 
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Joined: Sun Oct 02, 2011 9:31 am

Re: Byte-for-Byte verify fails using IFW but not IFL

Postby timg11 » Wed Jul 05, 2017 10:54 am

PS it would be great if a future version of IFW could include an algorithm to detect these DRAT failures and not fail the entire image for B4B verify.
I.E. if a block fails B4B check, then look up whether or not the specific failed bytes in that block are actually used by a file. If the bytes are not part of current files, ignore the error.

What B4B validation should be telling us is "are any bytes _that_are_part_of_a_file_ different"?
timg11
 
Posts: 157
Joined: Sun Oct 02, 2011 9:31 am

Re: Byte-for-Byte verify fails using IFW but not IFL

Postby TeraByte Support » Wed Jul 05, 2017 11:10 am

From http://www.terabyteunlimited.com/kb/article.php?id=151

Byte-for-Byte Validation Failure when using a SSD

If the SSD (ATA) does not support Deterministic TRIM (e.g. DRAT, RZAT) then
any data in allocated file system clusters that have been trimmed and only
allocated (not used or written to) can change (with no real change) and
cause the byte-for-byte validation to fail. Use a SSD that supports
Deterministic TRIM to avoid this issue. Alternatively, use a NVMe drive,
which requires consistent reads in trimmed areas as part of its
specification.


Basically, that is the nature of not having DRAT (should have never been an
option to not have it).

"timg11" wrote in message news:13979@public.image...

Well DRAT, it's a shame there is no workaround. I think my last 850 EVO is
still in the returnable period with Amazon, so back it goes for a Crucial or
Intel.

I propose a sticky announcement post at the top of this forum to the effect,
"Do not buy Samsung 800 series SATA SSDs if you plan to image with IFW or
IFL and plan to use byte for byte verification"

It looks like the Samsung NVMe SSD 950 using M.2 are OK. I have that in my
main development machine, and do not see any errors.

TeraByte Support
 
Posts: 2273
Joined: Thu May 05, 2011 3:37 pm

Re: Byte-for-Byte verify fails using IFW but not IFL

Postby BettyL » Sun Jul 30, 2017 5:05 pm

Please check my post IFW 3.06a Samsung 850 EVO success backup and restore viewtopic.php?f=4&t=2602, which may be relevant to this issue.Its not clear in this topic if Disable TRIM was used during backup.
BettyL
 
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Joined: Sun Jul 30, 2017 4:32 pm

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