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Send IDLE IMMEDIATE for warm boot.

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We must send either an IDLE IMMEDIATE or a STANDBY IMMEDIATE to drives
on warm boot so their SMART and other volatile data is
persisted. However, for a warm boot we don't want to send STANDBY
IMMEDIATE to some spinning drives because they will spin down. If
there's a lot of these drives on the system, that can cause a
thundering herd problem at startup time (that in extreme cases causes
timeout in device discovery).

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D12811
This commit is contained in:
Warner Losh 2017-10-30 03:25:22 +00:00
parent 0255bc1370
commit 50ee2e2aab
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=325117
1 changed files with 18 additions and 6 deletions
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24
sys/cam/ata/ata_da.c
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@ -3534,17 +3534,29 @@ adaspindown(uint8_t cmd, int flags)
static void
adashutdown(void *arg, int howto)
{
int how;
adaflush();
/*
* STANDBY IMMEDIATE flushes any volatile data to the drive so
* do this always to ensure we flush a cosnsistent state to
* the drive. adaspindown will ensure that we don't send this
* to a drive that doesn't support it.
* STANDBY IMMEDIATE saves any volatile data to the drive. It also spins
* down hard drives. IDLE IMMEDIATE also saves the volatile data without
* a spindown. We send the former when we expect to lose power soon. For
* a warm boot, we send the latter to avoid a thundering herd of spinups
* just after the kernel loads while probing. We have to do something to
* flush the data because the BIOS in many systems resets the HBA
* causing a COMINIT/COMRESET negotiation, which some drives interpret
* as license to toss the volatile data, and others count as unclean
* shutdown when in the Active PM state in SMART attributes.
*
* adaspindown will ensure that we don't send this to a drive that
* doesn't support it.
*/
if (ada_spindown_shutdown != 0)
adaspindown(ATA_STANDBY_IMMEDIATE, 0);
if (ada_spindown_shutdown != 0) {
how = (howto & (RB_HALT | RB_POWEROFF | RB_POWERCYCLE)) ?
ATA_STANDBY_IMMEDIATE : ATA_IDLE_IMMEDIATE;
adaspindown(how, 0);
}
}
static void