diff -ur linuxorig/drivers/scsi/sd.c linux-2.4.23/drivers/scsi/sd.c
--- linuxorig/drivers/scsi/sd.c	2003-12-15 18:32:06.000000000 -0500
+++ linux-2.4.23/drivers/scsi/sd.c	2003-12-15 18:35:18.000000000 -0500
@@ -108,6 +108,8 @@
 static int sd_detect(Scsi_Device *);
 static void sd_detach(Scsi_Device *);
 static int sd_init_command(Scsi_Cmnd *);
+static void sd_start (Scsi_Cmnd * SCpnt);
+static void sd_devname(unsigned int disknum, char *buffer);
 
 static struct Scsi_Device_Template sd_template = {
 	name:"disk",
@@ -154,6 +156,7 @@
 	struct Scsi_Host * host;
 	Scsi_Device * SDev;
 	int diskinfo[4];
+        char nbuf[6];
     
 	SDev = rscsi_disks[DEVICE_NR(dev)].device;
 	if (!SDev)
@@ -238,6 +241,8 @@
 				return -EFAULT;
 			return 0;
 		}
+		case SD_IOCTL_IDLE:
+			return (jiffies - rscsi_disks[DEVICE_NR(dev)].idle) / HZ + 1;
 		case BLKGETSIZE:
 		case BLKGETSIZE64:
 		case BLKROSET:
@@ -259,6 +264,16 @@
 			return revalidate_scsidisk(dev, 1);
 
 		default:
+			if (cmd == SCSI_IOCTL_STOP_UNIT) {
+				rscsi_disks[DEVICE_NR(dev)].spindown = 1;
+        			sd_devname(DEVICE_NR(dev), nbuf);
+/*				printk(KERN_INFO "%s: Spinning down disk.\n",nbuf); */
+			}
+			if (cmd == SCSI_IOCTL_START_UNIT) {
+				rscsi_disks[DEVICE_NR(dev)].spindown = 0;
+        			sd_devname(DEVICE_NR(dev), nbuf);
+				printk(KERN_INFO "%s: Spinning up disk.\n",nbuf);
+			}
 			return scsi_ioctl(rscsi_disks[DEVICE_NR(dev)].device , cmd, (void *) arg);
 	}
 }
@@ -311,6 +326,14 @@
 	    SCpnt->request.rq_dev, block));
 
 	dpnt = &rscsi_disks[dev];
+
+	/* Update idle-since time */
+	rscsi_disks[dev].idle = jiffies;
+
+	/* Spin up */
+	if (dpnt->spindown) {
+	   sd_start(SCpnt);
+	}
 	if (dev >= sd_template.dev_max ||
 	    !dpnt->device ||
 	    !dpnt->device->online ||
@@ -700,6 +723,20 @@
  * them to SCSI commands.
  */
 
+/*
+ * handle spinup of idle disks
+ */
+
+static void sd_start (Scsi_Cmnd * SCpnt)
+{
+    unsigned char cmd[12];
+    int old_use_sg = SCpnt->use_sg, oldbufflen = SCpnt->bufflen;
+    Scsi_Device * dev = rscsi_disks[DEVICE_NR(SCpnt->request.rq_dev)].device;
+    sd_init_onedisk(DEVICE_NR(SCpnt->request.rq_dev));
+    rscsi_disks[DEVICE_NR(SCpnt->request.rq_dev)].spindown = 0;
+    SCpnt->use_sg  = old_use_sg;
+    SCpnt->bufflen = oldbufflen;
+}
 
 static int check_scsidisk_media_change(kdev_t full_dev)
 {
diff -ur linuxorig/drivers/scsi/sd.h linux-2.4.23/drivers/scsi/sd.h
--- linuxorig/drivers/scsi/sd.h	2003-12-15 18:32:15.000000000 -0500
+++ linux-2.4.23/drivers/scsi/sd.h	2003-12-15 18:35:18.000000000 -0500
@@ -26,6 +26,8 @@
 typedef struct scsi_disk {
 	unsigned capacity;	/* size in blocks */
 	Scsi_Device *device;
+        unsigned long idle;     /* idle time in jiffies */
+        unsigned char spindown; /* is down */
 	unsigned char ready;	/* flag ready for FLOPTICAL */
 	unsigned char write_prot;	/* flag write_protect for rmvable dev */
 	unsigned char sector_bit_size;	/* sector_size = 2 to the  bit size power */
diff -ur linuxorig/include/scsi/scsi_ioctl.h linux-2.4.23/include/scsi/scsi_ioctl.h
--- linuxorig/include/scsi/scsi_ioctl.h	2003-12-15 18:33:30.000000000 -0500
+++ linux-2.4.23/include/scsi/scsi_ioctl.h	2003-12-15 18:35:18.000000000 -0500
@@ -14,6 +14,7 @@
 
 #define	SCSI_REMOVAL_PREVENT	1
 #define	SCSI_REMOVAL_ALLOW	0
+#define SD_IOCTL_IDLE 4746
 
 #ifdef __KERNEL__